Author Archives: Paula Ferreira

About Paula Ferreira

Paula is a meteorologist who is now a PhD student in Physics. You will notice that her posts are mainly about cosmology, astronomy and atmospheric science.

Eunice Foote: the first person to measure the impact of carbon dioxide on climate

We often think of climate science as something that started only recently. The truth is that, like almost all fields of science, it started a long time ago. Advancing science is often a slow and tedious process, and climate science is not an exception. From the discovery of carbon dioxide until the most sophisticated climate models, it took a long time to get where we are.

Unfortunately, many scientists who played an important role in this climate journey are not given the credit they deserve. Take, for instance, Eunice Newton Foote.

Eunice Foote. Credits: Wikimedia Commons.

Foote was born in 1819 in Connecticut, USA. She spent her childhood in New York and later attended classes in the Troy Female Seminary, a higher education institution just for women.  She married Elish Foote in 1841, and the couple was active in the suffragist and abolitionist movements. They participated in the “Women’s Rights Convention” and signed the “Declaration of Sentiments” in 1848.

Eunice was also an inventor and an “amateur” scientist, a brave endeavor in a time when women were scarcely allowed to participate in science. However, one of her discoveries turned out to be instrumental in the field of climate science.

Why do we need jackets in the mountains?

In 1856, Eunice conducted an experiment to explain why low altitude air is warmer than in mountains. Back then, scientists were not sure about it, so she decided to test it. She published her results in the American Journal of Science and Arts.

“Circumstances affecting the heat of the Sun’s rays”. American Journal of Science and Arts. Credits: Wikimedia Commons.

Foote placed two cylinders under the Sun and later in the shade, each with a thermometer. She made sure the experiment would start with both cylinders with the same temperature. After three minutes, she measured the temperature in both situations. 

She noticed that rarefied air didn’t heat up as much as dense air, which explains the difference between mountaintops and valleys. Later, she compared the influence of moisture with the same apparatus. To make sure the other cylinder was dry enough, she added calcium chloride. The result was a much warmer cylinder with moist air in contrast to the dry one. This was the first step to explain the processes in the atmosphere, water vapor is one of the greenhouse gasses which sustain life on Earth.

But that wasn’t all. Foote went further and studied the effect of carbon dioxide. The gas had a high effect on heating the air. At the time, Eunice didn’t notice it, but with her measurements, the warming effect of water vapor made the temperatures 6% higher, while the carbon dioxide cylinder was 9% higher. 

Surprisingly, Eunice’s concluding paragraphs came with a simple deduction on how the atmosphere would respond to an increase in CO2. She predicted that adding more gas would lead to an increase in the temperature — which is pretty much what we know to be true now. In addition, she talked about the effect of carbon dioxide in the geological past, as scientists were already uncovering evidence that Earth’s climate was different back then.

We now know that during different geologic periods of the Earth, the climate was significantly warmer or colder. In fact, between the Permian and Triassic periods, the CO2 concentration was nearly 5 times higher than today’s, causing a 6ºC (10.8ºF) temperature increase.


Eunice Foote’s discovery made it to Scientific American in 1856, where it was presented by Joseph Henry in the Eighth Annual Meeting of the American Association for the Advancement of Science (AAAS). Henry also reported her findings in the New-York daily tribune but stated there were not significant. Her study was mentioned in two European reports, and her name was largely ignored for over 100 years — until it finally received credit for her observations in 2011

The credit for the discovery used to be given to John Tyndall, an Irish physicist. He published his findings in 1861 explaining how absorbed radiation (heat) was and which radiation it was – infrared. Tyndall was an “official” scientist, he had a doctorate, had recognition from previous work, everything necessary to be respected. 

But a few things draw the eye regarding Tyndall and Foote.

Atmospheric carbon dioxide concentrations and global annual average temperatures (in C) over the years 1880 to 2009. Credits: NOAA/NCDC

Dr Tyndall was part of the editorial team of a magazine that reprinted Foote’s work. It is possible he didn’t actually read the paper, or just ignored it because it was an American scientist (a common practice among European scientists back then), and or because of her gender. But it’s possible that he drew some inspiration from it as well — without quoting it.

It should be said that Tyndall’s work was more advanced and precise. He had better resources and he was close to the newest discoveries in physics that could support his hypothesis. But the question of why Foote’s work took so long to be credited is hard to answer without going into misogyny.

Today, whenever a finding is published, even if made with a low-budget apparatus, the scientist responsible for the next advance on the topic needs to cite their colleague. A good example happened to another important discovery involving another female scientist. Edwin Hubble used Henrietta Swan Leavitt’s discovery of the relationship between the brightness and period of cepheid variables. Her idea was part of the method to measure the galaxies’ velocities and distances that later proved the universe is expanding. Hubble said she deserved to share the Nobel Prize with him, unfortunately, she was already dead after the prize announcement.

It’s unfortunate that researchers like Foote don’t receive the recognition they deserve, but it’s encouraging that the scientific community is starting to finally recognize some of these pioneers. There’s plenty of work still left to be done.

New map of the universe reveals 4.4 million radio sources in the northern sky

After providing 25,000 supermassive black holes, the LOw Frequency ARray(LOFAR) has released its second batch of data — and it’s even more exciting. An international team has now published results from radio observations between 120 and 168 megahertz from the northern sky.

A composition radio (LoTSS-DR2) and optical (Hubble space telescope) image of the “jellyfish galaxy” NGC 4858 which is flying through a dense medium that is stripping material from the galaxy. Credit: Ian Roberts/ LOFAR.

A flurry of data

LOFAR measures 1000 kilometers (621 miles) across, making it the largest radio telescope that operates at low frequencies (below 250 MHz). The telescope array spent 3,451 hours looking at the sky to generate the latest data, producing a whopping 7.6 petabytes of archives. The survey covered 27% of the northern sky, and the team estimates that 67% to 85% of the region will be observed by May 2023.

It’s a large-scale, unprecedented view of the Universe seen in radio waves.

Each dot in this video shows the location of some hugely energetic object in our Universe. This includes black holes, galaxies with bursts of star formation, and explosive merging events between some of the Universe’s largest groups of galaxies. The video shows the most detailed ever view of our radio Universe as revealed by LOFAR. Credits Frits Sweijen.

After compiling everything, the astronomers concluded they could detect 4,396,228 radio sources. Some could be galaxies bearing supermassive black holes since active galactic nuclei (AGN) are a source of radio waves. Or the objects are bright stars being born in our own galaxy.

Some of the objects are extremely far away, even billions of light-years away. Some are already known by scientists, like the W3/W4/HB3 star-forming region, first detected by the Herschel Space Observatory, and the Cygnus loop supernova remnant first detected by the Hubble Space Telescope. Others are only now being discovered.

A composition radio (LoTSS; purple), UV (GALEX; yellow) and X-ray (ROSAT; blue) image of the Cygnus loop supernova remnant. This spectacular structure in the Milky Way is something to look forward to in future LoTSS data releases as the survey is now beginning to explore our Galaxy. Credits Jennifer West.

Astronomer Timothy Shimwell, part of ASTRON and Leiden University, says the project has been very exciting to work on.

“Each time we create a map our screens are filled with new discoveries and objects that have never before been seen by human eyes. Exploring the unfamiliar phenomena that glow in the energetic radio Universe is such an incredible experience and our team is thrilled to be able to release these maps publicly. This release is only 27% of the entire survey and we anticipate it will lead to many more scientific breakthroughs in the future, including examining how the largest structures in the Universe grow, how black holes form and evolve, the physics governing the formation of stars in distant galaxies and even detailing the most spectacular phases in the life of stars in our own Galaxy.”

However, LOFAR has tons of data to classify, and computers aren’t always enough for the job — and you can help. The team created a project so anyone can contribute to the project. You can go to the Zooniverse website and identify galaxies and supermassive black holes, they have a tutorial in which you can learn how to classify the radio sources, once you finish you can start exploring the universe.

The study was published in Astronomy & Astrophysics.

Annie Jump Cannon: the legend behind stellar classification

It is striking that today, we can not only discover but even classify stars that are light-years from Earth — sometimes, even billions of light-years away. Stellar classification often uses the famous Hertzsprung–Russell diagram, which summarises the basics of stellar evolution. The luminosity and the temperature of stars can teach us a lot about their life journey, as they burn their fuel and change chemical composition.

We know that some stars are made up mostly of ionised helium or neutral helium, some are hotter than others, and we fit the Sun as a not so impressive star compared to the giants. Part of that development came from Annie Jump Cannon’s contribution during her long career as an astronomer. 

The Hertzsprung diagram where the evolution of sun-like stars is traced. Credits: ESO.

On the shoulders of giantesses

Cannon was born in 1863 in Dover, Delaware, US. When she was 17 years old, thanks to her father’s support, she managed to travel 369 miles all the way from her hometown to attend classes at Wellesley College. It’s no big deal for teens today, but back then, this was an imaginable adventure for a young lady. The institution offered education exclusively for women, an ideal environment to spark in Cannon an ambition to become a scientist. In 1884, she graduated and later in 1896 started her career at the Harvard Observatory.

In Wellesley, she had Sarah Whiting as her astronomy professor, who sparked Cannon’s interest in spectroscopy:

“… of all branches of physics and astronomy, she was most keen on the spectroscopic development. Even at her Observatory receptions, she always had the spectra of various elements on exhibition. So great was her interest in the subject that she infused into the mind of her pupil who is writing these lines, a desire to continue the investigation of spectra.”

Whiting’s obituary in 1927, Annie Cannon.

Cannon had an explorer spirit and travelled across Europe, publishing a photography book in 1893 called “In the footsteps of Columbus”. It is believed that during her years at Wellesley, after the trip, she got infected with scarlet fever. The disease infected her ears and she suffered severe hearing loss, but that didn’t put an end to her social or scientific activities. Annie Jump Cannon was known for not missing meetings and participating in all American Astronomical Society meetings during her career.


At Radcliffe College, she began working more with spectroscopy. Her first work with southern stars spectra was later published in 1901 in the Annals of the Harvard College Observatory. The director of the observatory, Edward C. Pickering chose Cannon as the responsible for observing stars which would later become the Henry Draper Catalogue, named after the first person to measure the spectra of a star. 

Annie Jump Cannon at her desk at the Harvard College Observatory. Image via Wiki Commons.

The job didn’t pay much. In fact, Harvard employed a number of women as “women computers” that processed astronomic data. The women computer at Harvard earned less than secretaries, and this enabled researchers to hire more women computers, as men would have need to be paid more.

Her salary was only 25 cents an hour, a small income for a difficult job to look at the tiny details from the spectrographs, often only possible with magnifying glasses. She was known for being focused (possibly also influenced by her deafness), but she was also known for doing the job fast. Simply put,

During her career, she managed to classify the spectra of 225,000 stars. At the time, Williamina Fleming, a Scottish astronomer, was the Harvard lady in charge of the women computers. She had previously observed 10,000 stars from Draper Catalogue and classified them from letters A to N. But Annie Jump Cannon saw the link between the stars’ temperature and rearranged Fleming’s classification to the OBAFGKM system. The OBAFGKM system divides the stars from the hottest to the coldest, and astronomers created a popular mnemonic for it: “Oh Be A Fine Guy/Girl Kiss Me”.


“A bibliography of Miss Cannon’s scientific work would be exceedingly long, but it would be far easier to compile one than to presume to say how great has been the influence of her researches in astronomy. For there is scarcely a living astronomer who can remember the time when Miss Cannon was not an authoritative figure. It is nearly impossible for us to imagine the astronomical world without her. Of late years she has been not only a vital, living person; she has been an institution. Already in our school days she was a legend. The scientific world has lost something besides a great scientist.”

Cecilia Payne-Gaposchkin in Annie Jump Cannon’s obituary.
Annie Jump Cannon at Harvard University. Smithsonian Institution @ Flickr Commons.

Annie Jump Cannon was awarded many prizes, she became honorary doctorate of Oxford University, the first woman to receive the Henry Draper Medal in 1931, and the first woman to become an officer of the American Astronomical Society. 

Her work in stellar classification was followed by Cecilia Payne-Gaposchkin, another dame of stellar spectroscopy. Payne improved the system with quantum mechanics and described what stars are made of

Very few scientists have such a competent and exemplary career as Cannon. Payne continued the work left from Cannon, her advisor, Henry Norris Russell, then improved it with minimum citation. From that, we got today’s basic understanding of stellar classification. Her beautiful legacy has been rescued recently by other female astronomers who know the importance of her life’s work.

The Milky Way collided with a galaxy in the past — and this shaped our galaxy

The Milky Way and Andromeda are on a collision course, a galactic smash-up of gargantuan proportions. But there’s not much reason why you should worry about this. For starters, it’s likely to happen some 4.5 billion years in the future — and also, as a new study found, our galaxy has merged with others before.

In fact, around 10 billion years ago with a dwarf galaxy called Gaia-Sausage-Enceladus (GSE) –  one of the most recent collisions.

A major event in the formation of the Milky Way with Gaia-Sausage-Enceladus, around 10 billion years ago.
Credit: ESA (artist’s impression and composition); Koppelman, Villalobos and Helmi (simulation); NASA/ESA/Hubble (galaxy image), CC BY-SA 3.0 IGO

The GSE was discovered with the European Space Agency (ESA)’s Gaia observatory. In the 22 first months of observations, Gaia found a distribution of 30,000 stars in a trajectory opposite to most stars. Their path in the galaxy resembles a sausage (hence the ‘Sausage’ in the name) and their brightness indicates they belong to a particular stellar population.

Recently, a team simulated the collision between the galaxies and tried to understand if it was head-on or did it involve a decaying orbit. The scientists based their simulation on both Gaia and Multiple Mirror Telescope (MMT) Observatory of the Smithsonian Institution and the University of Arizona. The idea is to create a simulation as close to reality as possible.

In the results, the team successfully obtained the structure present today and how the collision formed. Their analysis matches with the trajectories and composition of the stars that exist today. GSE was approaching the Milky Way in opposite direction from our galaxy’s rotation until the dwarf galaxy merged with its bigger neighbor. In other words, judging by these trajectories, the Milky Way and GSE have collided in the past.

Anatomy of the Milky Way. Credit: Left: NASA/JPL-Caltech; right: ESA; layout: ESA/ATG medialab

This study contributes to more information about the history of the Milky Way. We now have an idea of how our galaxy became the way it is today. Merging with Gaia-Sausage-Enceladus had about 500 million stars and the event provided 20% of our galaxies’ dark matter and 50% of its stellar halo – part of a galaxy that contains stars beyond the primary distribution. 

The study was published in The Astrophysical Journal.

The journey of galaxy clusters in billions of years

A new study modeled the dynamics and evolution of some of the largest known structures in the universe.

Extragalactic neighborhood. Credit: Wikimedia Commons.

Let’s take a moment to look at our position in the universe.

We are now living on a solar system orbiting the center of the Milky Way galaxy — which itself lies in the Local Group of galaxies neighboring a Local Void, a vast cluster of space with fewer galaxies than expected. Wait, we’re not done yet. These structures are part of a larger region that encompasses thousands of galaxies in a supercluster called the Laniakea Supercluster, which is around 520 million light-years across. 

A group of researchers has now simulated the movement of galaxies in the Laniakea and other clusters of galaxies starting when the universe was in its infancy (just 1.6 million years old) until today. They used observations from the Two Micron All-Sky Survey (2MASS) and the Cosmicflows-3 as the starting point for their study. With these two tools, they looked at galaxies orbiting massive regions with velocities of up to 8,000 km/s — and made videos describing those orbits.

Because the universe is expanding and that influences the evolution of these superclusters, we first need to know how fast the universe is expanding, which has proven to be very difficult to calculate. So the team considered different plausible universal expansion scenarios to get the clusters’ motion. 

Besides Laniakea, the scientists report two other zones where galaxies appear to be flowing towards a gravitational field, the Perseus-Pisces (a 250 million light-years supercluster) and the Great Wall (a cluster of about 1.37 billion light-years). In the Laniakea region, galaxies flow towards the Great Attractor, a very dense part of the supercluster. The other superclusters have similar patterns, the Perseus-Pisces galaxies flow towards the spine of the cluster’s large filament.

The researchers even predicted the future of these galaxies. They estimated the path of the galaxies to something like 10 billion years into the future. It is clear in their videos, the expansion of the universe affecting the big picture. In smaller, denser regions, the attraction prevails, like the future of Milkomeda in the Local Group.

The study has been accepted for publication in Astrophysical Journal.

If the atmosphere is chaotic, how can we trust climate models?

Before they can understand how our planet’s climate is changing, scientists first need to understand the basic principles of this complicated system — the gears that keep the Earth’s climate turning. You can make simple models with simple interactions, and this is what happened in the first part of the 20th century. But starting from the 1950s and 1960s, researchers started increasingly incorporating more complex components into their models, using the ever-increasing computing power.

But the more researchers looked at climate (and the atmosphere, in particular), the more they understood that not everything is neat and ordered. Many things are predictable — if you know the state of the system today, you can calculate what it will be like tomorrow with perfect precision. But some components are seemingly chaotic.

Chaos theory studies these well-determined systems and attempts to describe their inner workings and patterns. Chaos theory states that behind the apparent randomness of such systems, there are interconnected mechanisms and self-organization that can be studied. So-called chaotic systems are very sensitive to their initial conditions. In mathematics (and especially in dynamic systems), the initial conditions are the “seed” values that describe a system. Even very small variations in the conditions today can have major consequences in the future.

It’s a lot to get your head around, but if you want to truly study the planet’s climate, this is what you have to get into.

The Butterfly Effect

Edward Lorenz and Ellen Fetter are two of the pioneers of chaos theory. These “heroes of chaos” used a big noisy computer called LGP-30 to develop what we know as chaos theory today.

Lorenz used the computer to run a weather simulation. After a while, he wanted to run the results again, but he just wanted half of the results, so he started the calculations using the results from the previous run as an initial condition. The computer was running everything with six digits, but the results printed were rounded to 3 digits. When the calculations were complete, the result was completely different from the previous one.  

That incident resulted in huge changes for the fields of meteorology, social sciences and even pandemic strategies. A famous phrase often used to describe this type of situation is “the butterfly effect”. You may be familiar with the idea behind it: “The flap of a butterfly’s wings in Brazil can set off a Tornado in Texas”. This summarizes the whole idea behind the small change in the initial conditions, and how small shifts in seemingly chaotic systems can lead to big changes. 

Simulation of Lorenz attractor of a chaotic system. Wikimedia Commons.

To get the idea, Lorenz went on to construct a diagram that depicts this chaos. It is called the Lorenz Attractor, and basically, it displays the trajectory of a particle described by a simple set of equations. The particle starts from a point and spirals around a critical point — a chaotic system is not cyclical so it never returns to the original point. After a while, it exceeds some distance and starts spiraling around another critical point, forming the shape of a butterfly. 

Why is it chaotic?

If the atmosphere is chaotic, how can we make predictions about it? First, let’s clarify two things. Predicting the weather is totally different from predicting the climate. Climate is a long period of atmospheric events, on the scale of decades, centuries, or even more. The weather is what we experience within hours, days, or weeks. 

Weather forecasting is based on forecast models which focus on predicting conditions for a few days. To make a forecast for tomorrow, the models need today’s observations as the initial condition. The observations aren’t perfect due to small deviations from reality but have improved substantially due to increases in computation power and satellites.

However, fluctuations contribute to making things harder to predict because of chaos. There is a limit to when the predictions are accurate — typically, no more than a few days. Anything longer than that makes the predictions not trustworthy. 

Thankfully, our knowledge about the atmosphere and technological advances made predictions better compared to 30 years ago. Unfortunately, there are still uncertainties due to the chaotic atmospheric behavior. This is illustrated in the image below, the model’s efficiency is compared between the day’s ranges. The 3-day forecast is always more accurate, compared to predictions from 5 to 10 days. 

The evolution of weather predictability. Credits: Shapiro et al. (AMS).

This image also shows an interesting societal issue. The Northern Hemisphere has always been better at predicting the weather than the South.

This happens because this region contains a larger number of richer countries that developed advanced science and technology earlier than the Global South, and have more monitoring stations in operation. Consequently, they used to have many more resources for observing the weather than poorer countries. Without these observations, you don’t have initial conditions to use for comparison and modeling. This started to change around the late ’90s and early 2000s when space agencies launched weather satellites that observe a larger area of the planet.

Predicting the climate

Predicting the climate is a different challenge, and in some ways, is surprisingly easier than predicting the weather. A longer period of time means more statistical predictability added to the problem. Take a game of chance, for instance. If you throw dice once and try to guess what you’ll get, the odds are stacked against you. But throw a dice a million times, and you have a pretty good idea what you’ll get. Similarly, when it comes to climate, a bunch of events are connected on average to long-term conditions and taken together, may be easier to predict.

In terms of models, there are many different aspects of weather and climate models. Weather models can predict where and when an atmospheric event happens. Climate models don’t focus on where exactly something will happen, but they care how many events happen on average in a specific period.

When it comes to climate, the Lorenz Attractor is the average of the underlying system conditions — the wings of the butterfly as a whole. Scientists use an ensemble of smaller models to ‘fill the butterfly’ with possibilities that on average represent a possible outcome, and figure out how the system as a whole is likely to evolve. That’s why climate models predictions and projections like those from the IPCC are extremely reliable, even when dealing with a complex, seemingly chaotic system.

Comparing models

Today, climate scientists have the computer power to average a bunch of models trying to predict the same climate pattern, further finessing the results. They can also carry out simulations with the same model, changing the initial conditions slightly and averaging the results. This provides a good indicator of what could happen for each outcome. Even further than that, there is a comparative workforce between the scientific community to show that independent models from independent science groups are agreeing about the effects of the climate crisis.

Organized in 1995, the Coupled Model Intercomparison Project (CMIP) is a way of analysing different models. This workforce makes sure scientists are comparing the same scenario but with different details in the calculations. With many results pointing to a similar outcome, the simulations are even more reliable.

Changes in global surface temperature over the past 170 years (black line) relative to 1850–1900 and annually-averaged, compared to CMIP6 climate model simulations of the temperature response to both human and natural drivers (red), and to only natural drivers (solar and volcanic activity, green). Solid coloured lines show the multi-model average, and coloured shades show the range (“very likely”) of simulations. Source: IPCC AR6 WGI>

Ultimately, predicting the climate is not like we are going to predict if it will be rainy on January 27 2122. Climate predictions focus on the average conditions that a particular season of an oscillatory event will be like. Despite the chaotic nature of the atmosphere, thanks to climate’s time length and statistical predictability, long-term climate predictions can be reliably made.

Stunning satellite observations show Tonga eruption effects in unprecedented detail

The Hunga Tonga-Hunga Ha‘apai volcano erupted on January 14, causing massive shockwaves and tsunamis that lead to 3 deaths and caused substantial damage to the Tongan Islands. Thanks to satellite imagery, researchers were able to observe this process in stunning detail. Here are some of these observations.

Ashes and cooling

The eruption released vast quantities of aerosols into the atmosphere. These particles reached the stratosphere, some 9 miles (15 km) above the surface. The stratosphere is a dry part of the atmosphere without clouds or humidity — so everything that reaches the stratosphere has little to interact with and is easily observable from above. 

The ashes from volcanoes consist largely of sulfur dioxide; once this sulfur dioxide reaches the atmosphere, it filters out some of the solar rays, producing a cooling effect. This effect can be quite powerful. Nearly 31 years ago, the Pinatubo volcano, in the Philippines, released 15 million tons of sulfur dioxide into the stratosphere. This tremendous amount took about two years to be depleted through chemical reactions, temporarily cooling the atmosphere by about 0.6 °C on average around the globe. 

Pinatubo’s eruption was used as a source of misinformation by climate denialists who wanted to diminish human interference from global warming — a volcanic eruption only produces temporary effects. As a matter of fact, Pinatubo’s effect was predicted by a climate model, which confirmed the predictions from climate models as reliable sources.

Image credits: Japan Meteorology Agency.

The eruption of Hunga Tonga-Hunga Ha‘apai is not as strong as Pinatubo’s, but the ashes will cool the air a little bit. However, it’s important to keep in mind that this won’t have any significant effect on climate change.


When the volcano sent ashes flying into the air, it caused a disruption in the atmospheric pressure levels. Just like hitting a drum’s membrane, the explosion pushed the air and changed the air pressure globally.

Researchers monitor these pressure changes through instruments called barometers. But because the planet is very big, the sudden change in air pressure due to the eruption took a while to reach different parts of the planet. For instance, it took 15 hours to reach the University of Hertfordshire Observatory in the UK, which is 16,500 km (around 10,253 mi) away from the volcano and it was registered by their barometer.

The propagation of the wave becomes very clear when we piece together a series of barometer detections. This was registered by the United States’ station on January 15:

The eruption was also a source of waves in the atmosphere, sending concentric ripples traveling the planet’s atmosphere as if it is not such a big deal. A stunning animation of the event was produced by theNational Oceanic and Atmospheric Administration (NOAA)’s GOES-West satellite, displaying the waves traveling the atmosphere just after the eruption.

The initial atmospheric response to the eruption was captured by Mathew Barlow using NOAA’s GOES-West satellite infrared radiance data (band 13). This sequence is based on images taken 10 minutes apart, and colors show the difference in infrared radiance between each time step. Credit: Mathew Barlow/University of Massachusetts Lowell.

So where do these waves go? Well, if you’re a flat-earther, this may upset you. Because the Earth is round, the wave travels to the furthest point, until it reaches a point and becomes a wave source itself that travels all the way around again, gradually losing energy until it disappears. 

There were also some “eyewitnesses” of the process. Registered by the Gemini Observatory at Maunakea in Hawaii, the following video shows a bunch of clouds moving normally, but the thin ripples that appear in the sky were caused by the eruption waves.

Never before could we monitor the atmospheric response to events such as this eruption, this is thanks to the number of cameras we have everywhere and better sensors to register the impacts. We didn’t have a fast way to communicate before, in this case, a few hours after the activity was possible for scientists to share their observations and shock everyone on how interactive the Earth system is. Let’s wait for the next crazy atmospheric phenomenon to leave us in awe.

Science may not be the meritocracy we thought it to be: gender and race discrepancies are prevalent

In a study published in the Proceedings of the National Academy of Sciences (PNAS), researchers highlighted the disparities in the scientific community in the US. Simply put, the US scientific workforce is not representative of the population. Barriers to entry and participation prevent important segments of the population, especially when it comes to race and gender.

Concepción Feminist Mural in Madrid. Wikimedia commons.

Researchers investigated the representation of different groups between more than 1 million articles in the Web of Science between 2008 and 2019. The groups are racial categories constructed in the American society: White, Black, Asian, and Latinx. These categories were also divided by gender (male and female).

The data showed that women, Black and Latinx scientists are underrepresented in various different scientific topics, while White and Asian men are generally overrepresented. In Science, Technology, Engineering, and Mathematics (STEM) fields, Black, Latinx, and White women are underrepresented and Asian women have a medium representation. This is different in Psychology and Arts, both Asian women and men are underrepresented.

The most over-represented group in STEM are Asian men and, and the same carries in social sciences more related to economy and logistics topics. Black scientists are better represented only in research fields related to racial inequalities and African or African American culture. Something similar happens to Latinx authors that seem to be more involved in topics such as immigration, political identities, and racism. 

This graphic shows the representation of various racial, ethnic, and gender groups as published authors in various fields. It shows that Latino, Black, and white women are significantly underrepresented as authors in engineering and technology, mathematics, and physics publications and are heavily overrepresented in health fields. Credit: Diego Kozlowski/University of Luxembourg.

The authors also compared how specialized each group is. Asian scientists are more focused on a specific topic compared to White authors who are more scattered among the topics. In contrast, topics regarding gender identity and inequality are the focus of Black and Latinx women, emphasizing the gender role imposed in society and signaling that women are trying to shift perceptions in this field.

In terms of citation, Asian men are more cited in Social Sciences and are more likely to be involved in topics that are highly cited. In the Health topics, White authors are more cited, followed by Black, Asian, and Latinx. This is a clear confirmation that minoritized groups are more cited in topics less favored in the scientific community and are less cited in both lowly and highly cited topics.

These inequalities are indicative of the inequalities in American society. While this study focused on the US, this is a global problem that needs to be addressed. In addition to making academia fairer and more inclusive, research has also shown that diversity among research teams fosters innovation and more impactful research. For now, it appears the open and fair academia may not be all that open and fair after all.

Space rocks: the difference between asteroids, comets, and meteors

Some objects in our solar system don’t orbit the Sun as neatly as planets do. Instead, rocky objects of different sizes and shapes float around our solar system, and sometimes, get really close to Earth and even enter our atmosphere. We give these objects names like shooting stars, asteroids, or comets, but which is which?

Asteroids vs Comets

Image credits: Giulia Forsythe.

Asteroids are essentially rocks that orbit the Sun. Most are small, but some can be pretty big — like Vesta, which measures 525 kilometers across, or Ceres the largest asteroid in our solar system, with a whopping 946-kilometer diameter. Overall, though, asteroids are usually quite small, and their combined mass is approximately equal to (or perhaps even smaller than) that of the Earth’s moon.

Most asteroids can be found in or nearby the Main Asteroid Belt — an area between Mars and Jupiter whose gravitational field keeps the dangerous rocks trapped and keeps them from flying about in the solar system (thanks for that, by the way). There are over a million asteroids larger than 1 kilometer (0.6 miles) in diameter, and millions of smaller ones in the asteroid belt. However, it’s hard to study them because they are basically small rocks with nothing to light them up.

Comets, on the other hand, have ice in their interior, and when they get close enough to the Sun, some of that ice starts melting away. The melting helps form the comet’s tail, along with ionized particles from gas molecules that are excited by the solar radiation. The orbits of comets are abnormal, typically very elongated ellipses that make them come really close to the Sun and then go away for a long time. This is what happens to Halley which can be seen every 75 years from Earth. 

Image Credit & Copyright: Rolando Ligustri (CARA Project, CAST) and Lukas Demetz.

So the main difference between asteroids and comets is in their composition: asteroids are made of metals and rock, whereas comets also contain ice and dust. This can be traced back to where they formed (asteroids generally formed closer to the Sun, where it was impossible to keep their ice).


Trojans are a special group of asteroids that share a planet’s orbit. They are so-called co-orbital objects found near the Lagrange points (points of gravitational equilibrium) of planets or larger moons — the Lagrange points, L4 and L5, to be precise. These regions of equilibrium make it so that a collision with neighboring planets is nearly impossible.

Jupiter has two large groups of trojans, the Trojan Camp and the Greek Camp — yes, astronomers really like wordplay.  The system is in a constant astronomical dance: Jupiter’s gravity pulls the trojans towards it, the Sun (which is much larger but also much farther away) also pulls the trojans, and the result is the swarm rotating in the Lagrange point and never leaving the area.

The time-lapsed animation above shows the movements of the inner planets, Jupiter and both swarms of Trojans (green) during the time period of the Lucy mission. The L4 Trojans lead Jupiter in its orbit and the L5 Trojans follow. Credits: Astronomical Institute of CAS/Petr Scheirich

Believe it or not, Earth has its own trojans as well. One was studied by astronomers, although it doesn’t have a charming name. It’s called 2010 TK7 and it was detected by the Wide-field Infrared Survey Explorer (WISE). 2010 TK7 is thought to be 300 meters wide, but thankfully it is in a stable position not threatening us.

Edgeworth-Kuiper Belt and Oort Cloud

Now, let us focus on the comets’ “home”. Comets are found both in the Edgeworth-Kuiper Belt and the Oort cloud. Those are both very distant regions in the Solar System that are far enough from the Sun to allow solid ice to exist. 

Kuiper Belt and Oort Cloud. Credits: JPL/NASA.

The doughnut-shaped Edgeworth-Kuiper Belt is located beyond Neptune’s orbit. Scientists believe the region is what was left of material to make a planet, but Neptune was more efficient and got the larger stuff to form itself, so the smaller rocks remained there without being massive enough to coalesce.

Pluto and many comets can be found in the Edgeworth-Kuiper Belt. In fact, being beyond Neptune’s orbit and in resonance with it is one of the reasons why it Pluto has lost its classification of a planet. As a consolation prize, Pluto is the largest object in this region.

Meanwhile, the Oort Cloud is much bigger and even more distant. You can think of it as a sort of shell for the solar system, like how a traditional Chinese paper lantern surrounds a candle. The cloud is technically just a theory because astronomers can’t observe it directly yet, but there is a lot of indirect information that supports its existence. Based on this evidence, the Oort cloud appears to be populated mainly by comets, but there are some asteroids as well. Like the other rocky/icy objects regions, the Oort Cloud is thought to be a remnant of the early Solar System.

The only man-made objects to ever reach distances beyond Neptune are the Voyagers and Pioners spacecraft. Voyager 1 reached over 14,480,000,000 miles from Earth, over 155 times the distance between the Earth and the Sun (called an “astronomical unit”) — and yet this is not even close to the Oort cloud. The 44-year mission would still need to move another 1,845 astronomical units to get there, which will take nearly another 44 years based on its current speed.

New Horizons is the fifth spacecraft to traverse the Kuiper Belt, but the first to conduct a scientific study of this mysterious region beyond Neptune. Credit: NASA/JHUAPL/SwRI/Magda Saina

Shooting stars

So what about shooting stars? These are small bodies called meteors entering Earth’s atmosphere and heating up to the point they become bright. When some of their minerals survive entering the air, the meteorite is the piece of rock left that reaches the ground. 

“Shooting star” is a pretty vague term, and astronomers don’t really like to use it. Instead, they class these objects as either meteors or meteorites. Meteors are rocks that burn up completely before reaching the planet’s surface, whereas a meteorite reaches the surface intact (or at least some part of it does). Meteorites are also smaller than asteroids.

Whenever Earth moves closer to certain asteroids, or when a comet comes near us, the debris can form a meteor shower. When the asteroid or comet passes near us, the debris enters the atmosphere and burns. Most of the debris is as tiny as blueberries, in fact, Earth is bombarded by 5,200 metric tons of micrometeorites (smaller than 1 millimeter) a year, but because they are so small they aren’t a threat.

Since we are orbiting the Sun, we get close to the same location every year, so we have periodic meteor showers like Orionids, Geminids, and many others named after the constellation they will appear at. It is easier to see the showers under a dark sky, without city lights to interfere. Also, depending on whether the phenomenon will happen near the horizon or not, you may find trouble with buildings blocking your view.

Perseid meteor shower, Wednesday, Aug. 11, 2021, in Spruce Knob, West Virginia.

In the end, the differences between the rocks aren’t so difficult, right? The comet is icy different from the asteroids. Comets are periodic and can be seen every 80 years or so. Many asteroids are near Jupiter who keeps most of them there – phew. Meteors are small objects that enter the atmosphere and if some of them survive, the remains are meteorites.

What does the universe sound like? The eerie world of cosmic sonification

Light is more than just what we see. The light spectrum can provide information about astrophysical objects — and in different wavelengths, it can provide different types of information. We can observe the sky through X-rays, visible light, gamma rays — all of which are waves at different frequencies. For sounds, something similar happens: it exists in many frequencies. High pitched sounds have higher frequencies than low ones, which is why electric guitars sound higher than bass guitars, their frequencies are a lot higher.

So what would happen if you would turn light (or other types of astronomic data) into sounds? This is technically called sonification — the use of non-speech data to represent sounds. You basically take some type of data and translate it into pitch, volume, and other parameters that define sound.

It’s not as silly or unheard of as it sounds. Scientists convert things into sounds for a number of reasons. For instance, take the Geiger counter, an electronic instrument used to measure ionizing radiation. If the radiation is high enough, you hear an increase of repetitions in the click sound from the instrument. The same can be done with astronomical data, with many lines of code, scientists can translate astronomical data into sounds. So, without further ado, here are some of the coolest sounds in the universe.

The Pillars of Creation

In the sonification in the Eagle Nebula, you can hear a combination of both optical and X-ray bands. The pitches change according to the position of the light frequencies observed, the result reminds us of a sci-fi movie soundtrack. As we listen to the features from the left to the right, the dusty parts form the Pillars as a whir, it’s eerily apparent that we’re hearing something cosmic.

Sonification Credit: NASA/CXC/SAO/K.Arcand, SYSTEM Sounds (M. Russo, A. Santaguida)

The Sun

Using Solar and Heliospheric Observatory (SOHO)’s data, we can listen to our star’s plasma flowing and forming eruptions. The sound is pretty peaceful for a 5,778 K environment.

Credits: A. Kosovichev, Stanford Experimental Physics Lab


In one of Parker Solar Probe’s flybys, the spacecraft collect data from Venus’ upper atmosphere. The planet’s ionosphere emits radio waves naturally that were easily sonified.

Video credit: NASA’s Goddard Space Flight Center/Scientific Visualization Studio

Bullet Cluster

The Bullet Cluster is famous for being proof dark matter is out there. In its sonification, the dark matter part (in blue) is lower, while the matter part (in pink) has a higher pitch. This is one of the most melodic cosmic sounds you’ll ever hear, though it does have a distinctively eerie tune as well.

Sonification Credit: NASA/CXC/SAO/K.Arcand, SYSTEM Sounds (M. Russo, A. Santaguida).

A supernova

This sonification is different from the others. We hear the sounds emanating from the centre of the Tycho’s supernova remnant and continue with the sounds of the stars visible in that plane. Inside the remnant, the sound is continuous, outside we hear distinct notes which are the stars nearby. 

Sonification Credit: NASA/CXC/SAO/K.Arcand, SYSTEM Sounds (M. Russo, A. Santaguida)

Cosmic music

With a musical approach, the sci-art outreach project SYSTEM Sounds, not just sonify data, but also make sure the sounds are harmonic. It’s even better when nature provides naturally harmonical systems.

The most incredible sonification of all comes from the TRAPPIST-1 system, a relatively close system “just” 39.1 light-years away. Six of the planets orbiting the red dwarf are in an orbital resonance that means they pull each other in pairs and their rotation match in the integer ratios 8:5, 5:3, 3:2, 3:2, 4:3, and 3:2. So the first two planets influence each other gravitationally — for every eight orbits completed by TRAPPIST-1a, TRAPPIST-1b completes five. If it all sounds a bit confusing, look at the video below and it will make more sense

SYSTEM Sounds got the advantage of the harmony in the TRAPPIST-1 system and sonified the planets orbiting their star. In the audio, first, you hear each planet completing one orbit as a piano note. Then to emphasise the orbit resonance, the team added a drum sound when the planets matched in orbit. The result is a super cool song.

Created by Matt Russo, Dan Tamayo and Andrew Santaguida 2017.

This type of project shows a new perspective and a new way of looking at data. Much more than just taking photos and looking that them, this is a way to showcase the many nuances and differences often present in astronomic data. Furthermore, this work is excellent to include visually impaired people in astronomical observation, making the cosmos accessible for those who can’t see it. If you have a friend suffering from visual impairment who would like to know what space is like — here’s your chance to show them.

A collection of sonification is found in the Chandra X-ray Center’s ‘A Universe of Sound‘ and SYSTEM Sounds.

The asteroid Apophis will pass close to Earth in 2029. Here’s why this is a good thing

The asteroid 99942 Apophis, first discovered in 2004, caused a bit of a panic and was briefly considered a risk-impact object. In 2021, the risk was ruled out by new observations — although the asteroid will pass close to Earth, it won’t cause any real problems. But it could give us a good chance to study it.

In a study conducted by astronomers from the Orbital Dynamics Group from the Universidade Estadual de São Paulo (UNESP), Brazil, and from the Universidad Carlos III de Madrid in Spain, researchers suggest that Apophis’ 2029 fly-by offer a learning opportunity, enabling researchers to get an unprecedented view of what’s happening on the asteroid’s surface. 

This animation depicts the orbital trajectory of asteroid 99942 Apophis as it zooms safely past Earth on April 13, 2029. Credit: NASA/JPL-Caltech.

The distance between us and Apophis is currently about 38,000 kilometers, as tracked by the NASA Jet Propulsion Laboratory (JPL)’s Horizons — about 10 times closer than the Moon is to the Earth. The asteroid’s estimated size is about 340 meters wide, thanks to observations from the Arecibo Observatory data, but its size is not completely clear. 

In the present study, the team simulated what they believe is the approximate size and shape of Apophis to understand what happens in it. It turns out, Apophis is in trouble: the Earth and the Sun are a threat to small particles around the rock because of gravity and the pressure caused by the Sun’s radiation.

Because the asteroid is not a spherical object and has an irregular shape, some particles will be more tilted than others. As it moves about, parts of the asteroid surface with a high slope will face more pressure than the other which sets the course of some particle floating above the surface. It is like the wind on our faces — the air passes on our cheeks, contouring them and applying pressure as it tries to move to behind our heads.

A model of the Apophis asteroid. Image credits: Astronomical Institute of the Charles University: Josef Ďurech, Vojtěch Sidorin.

The researchers considered how Earth’s gravity could affect Apophis and they concluded that nothing drastic will change the shape of the asteroid — at most, Earth’s gravitational field will trigger small landslides on the asteroid. Solar radiation, on the other hand, will change things for the particles surrounding Apophis – like tiny moons. Particles with 15 centimeters considering Apophis’ density is low, survive the solar radiation, smaller than that won’t live to tell the story. With a higher density, the surviving chances increase for 5-centimeter particles.

The encounter will provide more information regarding the shape and composition of the asteroid in future studies. Until then, we just keep calendars marked for the closest approach in 2029 where we’ll definitely learn more about Apophis and other asteroids like it.

The study was published in Monthly Notices of the Royal Astronomical Society (MNRAS).

What is Plasma — the most common state of matter found in the universe

Although plasma is unstable in terrestrial conditions, it’s the most common state of matter in the universe, making up a large chunk of all the stars in the universe. It’s also pretty weird, posing many questions that researchers are still working to unravel.

Just like the energy of light is carried by photons, the oscillation of plasma is carried out by plasmons. Plasmons aren’t a particle per se, they’re something called “quasiparticles” — a physical concept that researchers use to treat excitations in solids as particles.

We’re taught early in school that the basic states of matter are solid, liquid, and gas. There are other exotic states that scientists discovered more recently (like a superfluid or a Bose-Einstein condensate, for instance), but those three are what we learn as the “main” states of matter. However, your primary school teacher may have missed another one: plasma.

Plasma has a lot to do with heat: add enough heat to solids and they become liquid, next liquid becomes gas. Finally, with enough energy to ionize atoms into a soup of electrons and ions (electrically charged atoms), you have plasma.

Plasma has some unique characteristics that emerge as a result of the way particles interact with each other in this state. Let’s have a look at them.

Plasmon and Debye Shielding

Consider some electrically neutral plasma — this means that, between the charged free ions and electrons, positive and negative charges cancel each other out. If we change the position of a few electrons, even if it’s only a few, the displacement will change the electric equilibrium, so the now-unbalanced ions will try to move to a position to restore equilibrium. Because opposite charges attract, when the electrons move, the positive ions try to pull them back and make everything organized again. In plasma, this oscillation happens until some equilibrium is reached. This phenomenon is called Langmuir waves.

If you add charged particles to the plasma, the ions and electrons rearrange themselves in order to reach a nearly neutral state. To do so, electrons create a sort of electromagnetic shield around the positive particle, repelling the positive ions from it. This is called Debye Shielding.

The region necessary to involve such a particle is called a Debye sheath — or an electrostatic sheath. This type of sheath appears in plasma because the electrons tend to have a much higher temperature than that of the ions.  This creates a layer in the plasma that has a greater density of positive ions, and hence an overall excess positive charge.

Positive ion sheaths around grid wires in a thermionic gas tube. Wikimedia Commons

Depending on the charge and the characteristics of the plasma, the sheath can be bigger or smaller. Scientists classify plasmas based on the size of this sheath — an “ideal” plasma has lots of particles per Debye sheath volume, while fewer particles make it harder for electrons to shield new particles.

The early universe was made of plasma

Plasma can get very weird — which is why it’s somewhat surprising that the entire universe was, at some point, plasma.

During the first 10 to 15 microseconds of the universe, it was filled with a super hot soup made of particles called gluons and quarks. Gluons are the “glue” that sticks quarks together to form protons, neutrons, and other larger particles. During that early period, the universe was nearly 2 trillion Kelvin hot. This is the hottest the universe has ever been.

The history of the universe by particle physics. Credits: Particle Data Group.

We can simulate such conditions in a particle collider. In these accelerators, scientists smash heavy gold or lead ions together to produce the quark-gluon soup (QGP) — the stuff that made up the early plasma universe. In such conditions, they learned that this state of matter behaves like a perfect fluid, not viscous like honey. 

The two places perfect to form QGP are the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory and at the Large Hadron Collider (LHC) at CERN. The ions are accelerated to 99.995% of the speed of light, and QGP exists just for a very small fraction of a second (nearly zero) before it condenses again to form heavier particles.

Scientists collect the data from the accelerator and try to explain the mess with quantum chromodynamics- a very complex theory that strives to describe one of the fundamental interactions in nature — the strong interaction.

This image shows the end view of a collision of two 30-billion electron-volt gold beams in the STAR detector at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. The beams travel in opposite directions at nearly the speed of light before colliding. (Credit: Brookhaven National Laboratory).


You don’t need to go into the lab to find plasma — simply go outside. We have the sun (during the day) and stars (during the night). On some days, you can even see it in the sky, in the form of lightning.

Plasma is also found scattered across the universe. Called the Warm–hot intergalactic medium (WHIM), there’s plasma of around a billion Kelvin found between galaxies. Around galaxies, there is a reservoir of diffuse gas in the form of plasma called the circumgalactic medium (CGM). This is usually hard for scientists to study because the gas has a very low density, but some simulations seem to try to understand the role of CGM in galaxy formation.

You may find plasma in planets as well, mostly in their magnetospheres – the regions of planets’ magnetic field affecting charged particles coming from space. The magnetospheres serve as protection from the solar wind, and in the case of the giant planets, these regions can be larger than the Sun. Inside Jupiter’s inside the dawn flank of the magnetopause, scientists found protons and heavy ions.

This view visualizes only the inner part of the magnetosphere. The complete Jovian magnetosphere is an enormous, tadpole-shaped structure that balloons out to dozens of Jupiter widths around the planet. In the direction away from the sun, the magnetotail extends as far as the orbit of Saturn. Wikimedia Commons.

Plasma is a special state of matter, it is easily found in the universe. Unlike the other states of matter, it comes with other special properties because it is made of charged ingredients. Thanks to plasma physics, we understand the early stages of the universe and astrophysical objects.

The first indirect detection of gravitational waves: the road to LIGO

Gravitational waves are disturbances in space-time generated by some of the largest and most energetic events in the universe. They propagate as waves from a source at the speed of light.

Artistic depiction of gravitational waves. Image credits: Charly W. Karl.

In Einstein’s general theory of relativity, gravity is considered a curvature of spacetime — a curvature caused by the presence of mass. The larger and more compact the mass is, the greater the curvature. For physicists, gravitational waves are also the wave-like solution of Einstein’s equations and the only way through which some phenomena in the universe can be observed.

For instance, when the orbits of two massive bodies change over time, this seemingly results in a loss of energy. But energy can’t be lost, so it must go somewhere — and the only way to explain that loss is that the energy is used to produce waves in space-time, emitting gravitational radiation.

The theory lined up well, but there was a problem: for decades, researchers couldn’t truly detect these gravitational waves, and without validation, the theory couldn’t be confirmed. That all changed in 2015, with the first gravitational waves (GW150914) being directly observed by the two Laser Interferometer Gravitational Wave Observatory (LIGO) detectors. Three years later, the three main scientists behind the detection received the Nobel Prize for the discovery. But researchers may have discovered gravitational waves way earlier, in 1982.

Hulse–Taylor binary

This image shows pulsed gamma rays from the Vela pulsar as constructed from photons detected by Fermi’s Large Area Telescope. Credits: Goddard Space Flight Center.

In 1974, two astrophysicists, (Russell Alan Hulse and Joseph Hooton Taylor Jr) were carrying out a pulsar survey at the Arecibo Observatory, a radio telescope with a 305 meter (1,000 ft) dome. You may remember Arecibo as that big telescope that collapsed to rubble in late 2020 due to underfunding and neglect. Pulsars are a type of compact stars that emit radio or X-ray radiation — they’re a sort of cosmic lighthouse that spins, and whenever it emits a signal towards the Earth, we can detect.

There’s an important reason why Arecibo was so big. The goal of radio telescopes is to detect radio waves — waves for which the wavelength can measure even more than the Earth’s radius. The sources of radio waves outside the solar system are really weak, so we need very big dishes to detect those objects — and Arecibo successfully detected something.

The scientists detected a ‘weird’ pulsar, later named PSR B1913+16 or the “Hulse-Taylor binary”. Researchers noticed that the pulsation period of this pulsar is not stable — it changes and returns to the original state every 7.75 hours. The only explanation for that change was that the pulsar is in a binary system, the pulsar was completing an orbit every 7.75 hours. They knew that thanks to the Doppler effect.

When a light source is moving away from us, its frequency is shifted to the red side of the visible spectrum — and when it moves towards us it is shifted to blue. By measuring the pulsar period, Taylor and Hulse were able to plot a velocity curve to help analyze the orbit and try to figure out who was the pulsar’s companion.

Two stars of different sizes orbiting the same center of mass. The spectrum can be seen to split depending on the position and velocity of the stars. The shift of Star A is greater than that of Star B because the tangential velocity is higher. The line width of Star B is greater than that of Star A because Star B is larger and more luminous. Wikimedia Commons

In their analysis, they observed that system does not have a circular orbit but an ellipse. In the end, they concluded the pulsar lived in a binary system with another compact star, but they could yet not conclude if it was also pulsar or not.

Gravitational waves

By now, you’re probably wondering what this all has to do with gravitational waves. We’re almost there.

Eight years later, without stopping the observations, Taylor and Joel M. Weisberg realized the orbital velocity was increasing, meaning the stars were accelerating. They had also improved their knowledge of the system and figured that both stars have nearly the same mass of 1.4 solar masses and that their orbit is tight, around 4.5 times the Sun’s radius (or 9 times the distance from the Earth to the Moon). The pulsar’s companion is probably another pulsar, they concluded, but we just cannot get its radio signal because the beams it emits are never pointed towards Earth.

The binary was the perfect candidate to test the gravitational waves solution to Einstein’s equations, but because we couldn’t get direct information from the waves themselves, Taylor and Weisberg used theory to indirectly connect the observations from the pulse’s period. They noticed that the orbital period between the stars was decreasing with time, which means it was losing energy — presumably to gravitational waves.

While Arecibo was still working, the observations continued, and 30 years later, the same theory continued to fit the estimated loss of the orbital period, hinting more and more that the binary is emitting gravitational waves. The jaw-dropping conclusion of the study is the almost perfect agreement between the points (in red below) and the theory (blue line) almost as if there isn’t a minimal mistake in Einstein’s theory. Although they didn’t have any direct observation, astronomers had most likely detected gravitational waves indirectly.

Orbital decay of PSR B1913+16.The data points indicate the observed change in the epoch of periastron with date while the parabola illustrates the theoretically expected change in epoch according to general relativity.

The discovery of the binary pulsar resulted in a Nobel prize in 1993 for Taylor and Hulse, but not for the gravitational waves indirect detection. PSR1913+16 has always been the observation that paved the way for the gravitational waves interferometer, with the binary it was almost certain that the theory was correct, scientists just needed to be lucky enough to observe the phenomenon. It happened and in 2017, the Nobel prize in physics was awarded to LIGO researchers for the first solid detection.

The Arecibo Observatory in Puerto Rico. Credit: NAIC Arecibo Observatory, a facility of the NSF

The Arecibo radio telescope collapsed a year ago. The iconic telescope that made the first detection of binary pulsars, and many others, fell to rubble as it struggled to obtain funding in recent years. The data collected by the telescope is still used by scientists, the most recent was published exactly one year after its collapse, the research tries to understand the history of galaxies with their stellar mass.

Illegal gold mining happening in plain sight on an Amazon river

Illegal mining in the Amazon is a growing threat to local communities, but it’s continuing to grow and expand, posing a threat not just to the environment but to people’s health as well. A few days ago, a rumour that gold was found in the Madeira river in the south of the Amazon rainforest sent would-be miners into a frenzy, with hundreds of rafts being spotted on the lake.

After a rather slow crackdown, the operations have now been stopped, but many fear miners are still active, but are now more careful about hiding.

Map of the Amazon Basin with the Madeira River highlighted.

The Madeira River is the biggest tributary of the Amazon river, the biggest in the world. Madeira alone contains40% of the fish species of all the Amazon basin, including several endemic species such as the Bolivian river dolphin. It’s 3,250 km (2,020 mi), during the rainy season its depth can reach 180 m (590 ft).

Fifteen days ago, around 300 hundred dredging rafts moved to the river due to the gold rumor. The activity is obviously illegal in such an important region of the Amazon basin — but that did little to stop miners.

The rafts appeared together in lines and placed themselves in plain sight as if nothing out of normal was happening. The rafts are equipped with pumps to suck the riverbed to find gold. Then, to make things worse, miners use toxic substances made of mercury to separate the gold from sand and other rocky material. The remains of the separation are then discarded in the river itself.

This situation is an environmental disaster waiting to happen, but the Brazilian government only started preparing on November 25, well after the presence of the rafts was clear. As the government made it a public statement it made most of the miners leave the area, until finally on November 27 the remaining rafts were burned down by the Federal Police.

Not so long ago, in 2018, scientists were ‘celebrating’ the decline of mining in the river. They published a paper discussing mercury pollution and attributed the concentration levels to be mostly from the ’80s when the activity was intense in the region.

Unfortunately, it is nearly impossible for the consumer to know where the materials used to make jewels come from. If it is connected to illegal mining it comes with human rights risks and environmental impacts. Some of the ecological impacts stated by scientists include the loss of land and natural vegetation, air pollution from the vehicles used, and noise pollution.

Eugenics: how bad science was used to promote racism and ableism

Eugenics is the idea to selectively ‘improve’ humankind by only allowing specific physical and mental characteristics to exist. It focuses on systematically eradicating ‘undesirable’ physical traits and disabilities, and although it has been long discredited as a science, some of its ideas are still surprisingly prevalent in today’s society.

A Eugenics Society poster (1930s) from the Wellcome Library Eugenics Society Archive. Wikimedia Commons.

In some forms, eugenics actually has a remarkably long history. Some indigenous peoples of Brazil practiced infanticide against children born with physical abnormalities, and in ancient Greece, the philosopher Plato argued in favor of selective mating to produce a superior class. The Roman Empire and some Germanic tribes also practiced some forms of eugenics. However, eugenics didn’t truly become a large-scale idea until the 20th century.

Progress didn’t just happen in Europe

The foundation of eugenics lies on racist beliefs and ideologies — and especially something called scientific racism: a pseudoscientific belief that tries to empirical evidence to support or justify racism.

In 1981, American paleontologist Stephen Gould wrote ‘The Mismeasure of Man’, a book in which he discusses the problems of the continuous belief in biological determinism that later became eugenics. He gave examples of the instances of scientific racism and how some scientists contributed to providing ‘evidence’ to the superiority of white people, shaping faulty beliefs for decades or centuries. In the book, you can find the a remarkable list of horrid theories and studies which the researchers insisted on putting one race above the other. 

The most famous ranking of races was developed by 19th-century physician Samuel George Morton. Morton, believing himself to be objective, used his collection of skulls of different American Ethnicities to compare cranial capacities and try to prove superior intelligence of one group over the other. His study was basically done by ranking average head sizes (which is not directly connected to intelligence) but mixed different heights in his samples, which induced an obvious bias to his analysis. The analysis was strongly skewed towards linking intelligence with white men, and Morton’s conclusion was that white men were the most intelligent race on the face of the Earth. Gould criticized Morton’s data (though he does mention that the bias may have been unconscious), noting that the analysis includes analytical errors, manipulated sample compositions, and selectively reported data. Gould classifies this as one of the main instances of scientific racism.

But it gets even worse. Colonialism was working hand in hand with the idea that Europeans were carrying out a ‘civilizing mission’. White Europeans were doing nothing but a generous act of ‘helping’ ‘inferior’ races to develop and become civilized. This patronizing notion is easily debunked with historical evidence. For instance, we know Mesoamerican and Andean civilizations were empires and they didn’t need foreign influence to achieve progress. Take Stonehenge for instance, a monument in England we believe was built around 3000 or 2000 BC. Though very impressive and with enough complexity, it is not as advanced as the Giza pyramid complex in Egypt, which was created around nearly the same period, proving how civilizations were evolving independently. 

Social Darwinism

Image credits: Gennie Stafford.

Another interesting aspect of eugenics is so-called social Darwinism. Social Darwinists believe that “survival of the fittest” also happens in society — some people become powerful in society because they are somehow innately better.

Social Darwinism was invented by one of the founders of eugenics, Sir Francis Galton, one of Charles Darwin’s cousins. He believed that eugenics should ‘help’ the human race to reach its ultimate ‘potential’ accelerating the ‘evolution’ by eliminating the ‘weak’ and keeping the ‘appropriate races’. 

The problem is it does not fit any scientific evidence. First, genetics has clearly shown that we don’t have a separation in races, race is rather a social construct more than a genetic one. Differences do exist, but they have to do with common ancestry. In our species, we share 99.9% of our DNA, regardless of race. As a result, one ethnicity is not better than the other in anything, not in appearance, behavior, or intelligence.

The other misconception lies in natural selection itself. Evolution, for humans, is a slow process, it takes time for a genetic trait to become dominant in a species. Social change, on the other hand, is much faster; regimes fall, presidents change, policies change. The changes in society can be beneficial or not for some people, maybe everyone will have easy access to vaccines and survive an epidemic, while in a different regime people can get sick for not having these basic rights. Or worse, shorten the number of people simply because they do not have enough to eat. This has nothing to do with a group being stronger than the other, but the choice of leaving some unassisted. Simply put, social Darwinism has little scientific evidence to back it up — and a lot of evidence against it.

How technology fits in

Morton’s ideas are obviously flawed, but scientists took them as an objective analysis for decades — and that’s when the chaos started. One scientist cites the other, and the other, propagating false ideas and sending their echo through history affecting millions of lives for years. More theories like those emerged, with developments that come with the evolution of science, but the insistence of ranking white men as the ‘apex predator’ perpetuated. Even leading scientists can fall prey to racist ideas, and mask them as scientific racism.

Even with modern machine learning and big data, these ideas can still continue to propagate. If the scientists involved don’t make sure that their code is not being susceptible to biases, the computer won’t be objective. That happened to a machine learning routine using data from hospitals in the US. The algorithm wanted to find patients with risks, one of the easy ways is to look for the amount of money spent by a patient in one year. Seems reasonable, but the problem is the model excluded a large number of black people, for obvious reasons, our society is biased. The fact that this particular system involves money has nothing to do with the patient’s condition. 

Machine learning is based on statistics, and some of the fathers of statistics are intertwined with eugenics. If you ever took a statistics course, you may have heard the name ‘Pearson’. Karl Pearson developed hypothesis testing, the use of p-values, the Chi-Squared test, and many other useful tools for science still used today. However, the scientist held strong beliefs in Social Darwinism, a distorted idea that due to natural selection some groups struggle more because in the end ‘the stronger survive’. Pearson even supported wars against ‘inferior races’. In 2020, the University College London renamed lecture halls and a building which originally honored Pearson and Francis Galton.

The search for the ‘special mind’

Besides ethnicity, the next eugenicist target is intelligence. The French psychologist Alfred Binet invented what we know today as the first version of the IQ test. He wanted his test to be used to help kids at school — those who performed poorly would be sent to special classes to get help adapting. He didn’t want that to be a label to segregate people. However, his ideas were distorted by some scientists in the USA. In the American continent, the test was used to reinforce the old fallacies for ranking people, even becoming a mechanism to select immigrants. 

In time, the IQ test became the one you know today. The problem with it is that it’s often used to segregate people, without accounting for cultural or socioeconomic factors that could affect IQ scores. That’s not all: American psychologist Henry Goddard, the one responsible for corrupting Binet’s ideas, defended the idea that ‘feeble-minded’ people should not have children. In addition, he and other gentlemen chose words like ‘idiot’, ‘moron’, and ‘feeble-minded’ to classify people — words we still use today to insult someone.


The ultimate goal of eugenics is perpetuating only the ‘good’ genes — which means not allowing those who have ‘bad’ genes to reproduce.

This led to forced sterilizations in people with mental disorders. The most famous example was the case Buck vs. Bell in the US in 1927. Most of the over 60,000 sterilizations happened in the United States in people whose conditions were labeled as ‘feeble-minded’ and ‘insane’ between the 1920s and 1950s.

These procedures were typically carried out in asylums or prisons, with a medical supervisor having the right to decide whether the inmates’ reproductive systems should be altered or not. The practice is now considered a violation of their rights — and the motivation that “it would improve inmates’ lives” is considered bogus, as is “concern about the financial burden the inmates would provide if they had children”, punishment, and of course “avoid the reproduction of the unfit”. All these with California’s law that the person had no right for objection or appeal.


A lot happened from Goddard’s time to the 1930s and 1940s when autism was discovered. Know the famous guy, Hans Asperger? Well, he was a nazi Austrian pediatrician known for understanding one ‘type’ of autism, later known as Asperger Syndrome. The diagnostic criteria for Asperger Syndrome were removed from the  Diagnostic and Statistical Manual of Mental Disorders in 2013. There are no longer sub diagnoses, it is all called Autism Spectrum Disorder (ASD).

Asperger observed there were autistic children who were more ‘adaptable’ to the social norms, they could act ‘normal’, so he labeled those children as “high functioning”, while others were “low functioning”. The low functioning was considered a burden and not fit for the Third Reich because they couldn’t do the tasks of a “normal” person. In other words, they wouldn’t be profitable. Asperger would then transfer these ‘genetically inferior’ children to the ‘euthanasia’ killing programs, making the choice of who was worth living and who wasn’t. Next time you meet people suffering from autism, ask if they want to be connected to that idea before calling anyone low functioning/high functioning/aspie — spoiler, they almost definitely don’t.

Genetic research can be eugenist, without mentioning the word or directly defending the idea. Nobody seems to ask autistic people what types of research could be done in order to make their lives better, it is usually a concern on ‘how parents should not have a burden’ – pay attention to the advertisements, do they display autistic people in successful positions, or are they pictures of children with their parents? 

More recently, Spectrum10k research was paused. The UK-based researchers wanted to interview and collect DNA from autistic people and their relatives. The autistic community was not consulted and questioned on who the data would be shared with. They realized people involved in the project had a history of questionable research regarding autistic DNA, so advocates protested and the study was paused with the promise they will listen to autistic people.

“People with disabilities are genuinely concerned that these developments could result in new eugenic practices and further undermine social acceptance and solidarity towards disability – and more broadly, towards human diversity.”

Said Catalina Devandas on 28 February 2020, a UN Special Rapporteur on the rights of persons with disabilities.

Gould saw a problem with many ideas back in the 90s, he edited the book to add the biased ‘research’ of his time, with the hope to alert scientists not to make those same mistakes. It is evident that our world of today has no more space for racist/ableist science like thise, so why is it ok for labels which came from those eras to be in machine learning, the therapists’ offices, and schools? It’s about time to cut the eugenics out of our civilization.

Astronomers may have detected a planet orbiting a triple star system

The GW Orionis star system has three stars orbiting each other. Now, researchers think they may have found a planet in this dancing star trio — and if it’s true, it could teach us a few things about how planets are formed.

GW Orionis, a triple star system with a peculiar inner region. Unlike the flat planet-forming discs we see around many stars, GW Orionis features a warped disc, deformed by the movements of the three stars at its centre. This composite image shows both the ALMA and SPHERE observations of the disc. Image Credits: ALMA (ESO/NAOJ/NRAO), ESO/Exeter/Kraus et al.

Binary star systems are well known to both scientists and science fiction fans. Although our own solar system has one star, systems with two or even three stars are not unusual. Between 40 and 50% are binaries and 20% are triple stars systems. If you’re an astronomer studying these solar systems, describing them is more complicated than those with a single star.

For binary systems, researchers use the so-called two-body problem to describe how the stars will move and gravitate around each other. However, the three-body problem is far more difficult.

The notoriously difficult three-body system has no exact solution. When the three objects have similar mass, they function in a seemingly chaotic, dynamical system whose motion is very complex and difficult to describe. Astronomers use intense computational simulators to estimate the orbits and motions in such complex systems especially when they are far away and difficult to describe.

Movement of three equal mass bodies initially at rest, showing the unmoving centre of mass

The GW Orionis system may possibly be the first triple star system we’ve ever observed that has a planet orbiting it. Two of the stars are a spectroscopic binary system, as revealed by the Doppler effect of their motion: one star is farther away from us and it appears redder, while the other is closer and appears bluer. The binary pair is separated by the same distance as that between Earth and the Sun. The third star is 8 times that distance from the binary. This type of distribution is called a hierarchical trinary, where two stars orbit each other and a third one orbits them both.

The instruments from Atacama Large Millimeter Array(ALMA), in Chile, detected a cloud of dust and gas surrounding the system. In another Chile-based observatory, the Paranal Observatory, instruments observed the deformity in that cloud. It is not a horizontal disk orbiting a star, but a bunch of messy ‘rings’ wrapped around the inner structure.

ALMA, in which ESO is a partner, and the SPHERE instrument on ESO’s Very Large Telescope have imaged GW Orionis, a triple star system with a peculiar inner region. The new observations revealed that this object has a warped planet-forming disc with a misaligned ring. In particular, the SPHERE image (right panel) allowed astronomers to see, for the first time, the shadow that this ring casts on the rest of the disc. This helped them figure out the 3D shape of the ring and the overall disc. The left panel shows an artistic impression of the inner region of the disc, including the ring, which is based on the 3D shape reconstructed by the team. Credit:ESO/L. Calçada, Exeter/Kraus et al.

The disk has three main rings, one closer to the triplet and two others misaligned from the inner one. The tilt is caused due to the orbits of the stars, the third outer star is not in the plane as the binary, so the motion of the gas around them is distorted and tilted as well.

But the distorted gas would not be like this only due to the gravitational interaction between the stars. So the team simulated a scenario in which a planet would be between a big gap between the inner rings, in an orbit that is the same plane as the binaries. Their results showed that the planet needs to be massive for that, something like Jupiter which could gain mass from the cloud, in crazy cataclysmic sets of events the planet moves to an inner orbital position. It is also possible that another planet forms from the inner ring which has 30 times the mass of our planet.

All this is a combination between observations and the simulation, whether this is the best explanation to what we have measured or not is left for future detections. The system is enormously complex and difficult to describe mathematically, even with simulations it is hard to represent it perfectly. For now, this is already amazing progress astronomers are making towards understanding this complex, far-away system.

The study was published in MNRAS.

Astronomers zoom in on mysterious V838 Monocerotis red nova

In 2002, astronomers detected a new ‘star’ in the Monoceros constellation, some 3,300 light-years away from Earth. The star is called V838 Monocerotis and was initially classified as a variable star — a star with varying brightness. However, it became apparent that the star was rather unusual.

Evolution of the light echo around V838 Monocerotis. Credits: NASA/ESA Hubble Space Telescope.

Astronomers observed that the light intensity of this star resembled a nova — an explosive star that’s not quite as cataclysmic as a supernova. However, three months later, the star started emitting massive amounts of infrared light, so it didn’t really seem to be a nova after all. Ultimately, V838 Monocerotis was finally classified as a luminous red nova — a stellar explosion that occurs when two stars merge.

Now, researchers have captured new details about this mysterious star.

A cascading stellar event

When the merging happened, it produced one of the most spectacular images you can imagine. As the gases and dust traveled outward from the epicenter of the event, they scattered light from the explosion itself. The scattered light was then deflected by the molecular cloud, taking a little longer to reach us compared to the light coming directly to Earth — a phenomenon called a ‘light echo’.

After the stars merged, the remnant left behind is likely a red supergiant that’s dozens or even hundreds of times the size of the sun — big enough to fill Mars’s entire orbit. However, because the event took place very far away, it took years for us to observe the formation of ions from the dust ejected by the merger. The ejected material expelled during the collision traveled through space and encountered another star in the system, a third companion B-type star – this one, in particular, is a BV3 star which is nearly 8 times more massive than the Sun.  

In a recent study, astronomers found direct evidence of this third star for the first time, 17 years after they observed the red nova going boom. They used observations from the Atacama Large Millimeter/submillimeter Array (ALMA) interferometer from 2019. ALMA’s data helps scientists ‘see’ what is happening in the system in terms of dust, gases, and gathers information about the stars themselves. When the material was close enough to the giant’s companion, it became ionized by the photons emitted from this star, and that helped the researchers to learn details about the B star.

Their results show that the B-star companion’ gravity pulls some of the gas away from us, making them appear redshifted. They also learned that this companion is embedded in the ejected cloud. It orbits its giant sibling over a 1000 year period from a distance greater than 230 times our distance from the Sun so that the gas only reached it 3 years after the nova event. 

The animation illustrates the merger and subsequent mass loss in the famous red nova V838 Mon. The events are followed up to an epoch of ALMA observations of this source. The animation was made by Piotr Mikielewicz (

Researchers have also learned that the molecular cloud is traveling at 200 km per second (approximately 124.3 miles per second). With the help of spectroscopy, scientists can determine the chemical composition of the cloud because it is the preferred absorption of radiation observed by ALMA’s instruments. It is made of carbon monoxide, silicon monoxide, sulfur monoxide, sulfur dioxide, and aluminum monohydroxide.

Future observations will provide more evidence of novas ejected material and their formation through mergers thanks to millimeter/submillimeter observations, something scientists didn’t have access to 20 years ago. 

The study was published at Astronomy & Astrophysics.

Why do stars twinkle, or do they twinkle at all? For astronomers, this is important

When we look at the sky, we see different types of objects. Some are man-made (like the International Space Station), some are from our solar system (like Venus or Saturn), but many are twinkling, shiny objects — of course, stars from outside our solar system.

Stars have fascinated humans since time immemorial, especially because sometimes, they seem to twinkle. Stars don’t actually twinkle per se — the twinkling we observe here has more to do with the atmosphere on Earth rather than the stars themselves. There are three main factors that influence how stars “twinkle”, and to truly understand them, we need to take a short dive into some atmospheric physics.

A view of the stars photographed at Klein Flintbek. Behind the tree with the red lights is the Kiel telecommunications tower. The light pollution (Kiel) is also easy to see. Credits: Fabian Horst.


The first physical phenomenon that makes stars appear to twinkle is turbulence.

We observe stars that are far away because the light that they emit reaches our eyes (or telescopes). But in order to do that, it must first pass through the atmosphere. That means that light is indirectly subjected to phenomena that affect the Earth’s atmosphere.

Turbulence is a phenomenon that often happens on smaller scales. In the atmosphere, we have large-scale phenomena like cold fronts or hurricanes happening every day, but inside these events, turbulence is significant on a small scale. So cold fronts bring large thunderstorms, the clouds within the front can make the sky turbulent, and that’s when the airplane pilot tells you “Ladies and gentlemen, we’re experiencing some turbulence.”

Image credits:

There are several types of turbulence, including one called thermal turbulence — which happens when there is a mix between hotter and colder air. This could happen whether the sky is cloudy or not. When a mass of air in the atmosphere is hotter than its surroundings, it starts to rise, creating convective currents. Basically, you end up with moving columns or pockets of heated air that arise from warmer surfaces of the earth.

These moving pockets of air can create turbulence, and in the process, they also distort light that passes through them.

When it comes to stars, twinkling is caused by the passing of light through different layers of the turbulent atmosphere. This is more pronounced near the horizon than directly overhead since light rays near the horizon pass through denser layers of the atmosphere, but twinkling (technically called scintillation) can be observed on all parts of the sky.

But there’s more to this story.


Schematic diagram illustrating how optical wavefronts from a distant star may be perturbed by a layer of turbulent mixing in the atmosphere. The vertical scale of the wavefronts plotted is highly exaggerated.

When light passes through any medium (including the Earth’s atmosphere), some of it is reflected back, while some passes through the atmosphere, but at a different angle — something called refraction. When the atmosphere is turbulent in a region, the refraction angle is not constant, so light can change path quickly. 

Altering the refractive index changes the apparent position of objects, just like the straw in a glass of water experiment, it looks bent. So the turbulent sky, constantly changing the refractive index makes stars appear to be moving, so they twinkle, or scintillate

The different refraction index in water (versus air) makes objects appear bent. If this is happening quickly and in multiple places, it can make objects appear twinkling.

Due to scale differences, if an astronomical object is large enough compared to the turbulence, it won’t affect the way we see it. But the light of a smaller object (or one that’s farther away) will be affected as it crosses the turbulent air. That’s the reason why planets twinkle less (or almost don’t twinkle at all) — they are closer and it makes them ‘bigger’ compared to the turbulence.

Fortunately, atmospheric scientists developed a way to monitor changes in the refractive index of the atmosphere due to turbulence. They use instruments to measure the turbulence and use it to try to estimate a future outcome.

Different skies

For astronomers, twinkling can be quite problematic. So they look for the “best sky” to avoid the phenomenon. Usually, this means an environment whose climate is very dry. When that’s not possible, they try to find the dryness by placing the instruments at a high altitude. Whenever is possible to combine altitude and mostly dry weather, they have a good spot for a telescope.

In the images above we see the difference very clearly: both skies were clear when the images were taken, but one (on the left) was less turbulent than the other (on the right). On the left, we see a video of a star recorded on Mount Fuji in Japan — the star appears to be bouncing chaotically due to a turbulent sky. On the right, we see a recording of the same star taken on the Andes Mountains in Chile, a very dry, high-altitude area; the star bounces, but much less than in the Japanese images.

A map of all ground-based telescopes that the MST have procured to observe during K2C9. Credits: 10.1088/1538-3873/128/970/124401

So stars don’t exactly twinkle, but they do appear to twinkle from here on Earth. For astronomers, though, making sure they eliminate the “twinkling” is important.

Of course, if you set your telescopes in space, you don’t have these problems because your observation point is above the atmosphere. But even here on Earth, astronomers are careful to pick the best locations for placing large optical telescopes. They typically look for the driest areas, at the highest altitude possible, without any light pollution. There’s another consideration: because the air is usually flowing from west to east because of Earth’s rotation, a way to avoid pollution is placing telescopes on west coasts or in ilands in the middle of the ocean. This rules out the vast majority of places on Earth, which is why astronomers are so particular about where they place their telescopes.

Unusual collision triggers supernova explosion in binary star system

When stars collapse under their own gravity, they can leave behind a neutron star or black hole — provided that the star is massive enough. In a binary star system, this can lead to some pretty wicked interactions.

Fast-moving debris from a supernova explosion triggered by a stellar collision crashes into gas thrown out earlier, and the shocks cause bright radio emission seen by the VLA. Credit: Bill Saxton, NRAO/AUI/NSF

When stars collapse under their own gravity, they can leave behind a neutron star or maybe a black hole — provided that the star is massive enough. Neutron stars and black holes are called compact objects by astrophysicists. They are extremely dense, but not necessarily extremely massive. For instance, some black holes can be less massive than stars, at 5 – 10 solar masses — while supergiants like Betelgeuse can have 19 solar masses.

Just because our Sun is a lone wolf star doesn’t mean all the other stars are alone out there. In fact, many stars, (especially massive ones with more than 8 solar masses) are in binary star systems.

A binary star is not just one star orbiting the other neatly like in the solar system models we see in school — what celestial bodies are actually orbiting is each other’s center of mass. If a star is much more massive than the other, it would be the leader of the orbital dance and pull the center of mass closer to it — just like in our case, the Earth is considerably more massive than the Moon, so the center of mass is closer to our planet.

Binaries can form in stellar nurseries, dense molecular clouds that can collapse and form stars. If one of the two is substantially more massive than the other, it can make things extra interesting. What sometimes happens is that the more massive star holding the stronger gravitational field can start accreting (stealing) gas from its companion. In the case of neutron stars, they can do that even when their companion is bigger. We also know that black holes can also munch on an orbiting star, as was reported by the Laser Interferometer Gravitational-Wave Observatory (LIGO) detection GW200105 in 2020. The other scenario (where a star would absorb its more massive partner) is hard to imagine.

Researchers detected a radio source called VT J121001+495647 from the Very Large Array Sky Survey and later looked for the same event using different telescopes, and found X-ray signals. The X-ray emission lasted 15 seconds, with 4 trillion trillion trillion joules per second, the only objects powerful enough to emit this much energy in the X-ray band are supernovae. 

The newly-discovered binary system, 480 million light-years away from Earth has two objects that were probably formed together but had very different life cycles: one of them was probably an ordinary star with regular nuclear fusion activity, like most main sequence stars, while the other is more mysterious. It could be a neutron star or a black hole, but probably, the result of a very hot fast-burning fuel life-cycle that ended in a compact object.

The reason we see a radio emission is that the big star (not the compact object munching on it) went from the normal phase to the supergiant phase. Simply put, it grew in size, (just like our sun will, at some point, grow enough to envelop Earth), and eventually, the companion was wrapped by it. A cataclysmic dance started, the denser companion messed with the core collapse of the bigger friend. Ultimately, this will probably end in one big boom, astronomers explain.

“The companion star was going to explode eventually, but this merger accelerated the process,” said Dillon Dong – leading author of the discovery.

The compact object remained inspiraling towards the star’s core, ejecting mass which formed a disk with a jet coming out of its axis – in a doughnut shape. When finally reaching the core of a titanic boom, the collapse of the star’s core forms a supernova.

This was the first time scientists found evidence of a star eating a neutron star/black hole, something only discussed theoretically until now. Hopefully, future observations will shed more light on this unusual process. The study was published in Science.

A different way of looking at the sky — Brazilian ethnoastronomy and its unique constellations

We often regard the invention of astronomy from a Greek perspective — after all, most of the official constellations and planets are named after Greek mythology. The names are connected to epic stories that permeated ancient people’s imagination, making it easier to pass the information to a younger generation. However, astronomy was not exclusive to western philosophy– other people used astronomy in their lives as well, and they had their own, different systems.

Archeoastronomy focuses on the way ancient civilizations used astronomy, either for religious purposes or scientific observations. It is known from archeoastronomy that Mesoamerican cultures used their architecture as a form of measuring time. Their legacy is studied by ethnoastronomy.

The Southern Cross, Milky Way and Carina Nebula, viewed from Kenya.Credit…Babak Tafreshi/National Geographic Society, via Corbis

We know a few examples of different astronomical classifications. The Aboriginal culture has a constellation called Emu, the Australian ostrich, between the Southern Cross and Scorpius. Similarly, in African Tswana and Venda traditions, the Southern Cross is a group of giraffes.

Brazilian indigenous groups also have their own astronomical system. Most of the information we now know can be traced to the moment when the Europeans started interacting with these indigenous people, also through more careful observation from explorers who visited the Americas as part of their academic lives. For most of the outsiders, the indigenous culture was seen as inferior, limited, and they formed a narrative  in order to fit in the eurocentric view:

“With the true God, who created heaven and earth, they don’t care. They believe, with a long tradition, that heaven and earth have always existed. In fact, they know nothing about the beginning of the world, they just narrate that there was once a vastness of water in which all their ancestors drowned. Only a few there escaped on a boat and others on tall trees. I think it must have been the flood.” (Hans Staden between 1547 and 1548)

However, although Europeans tried to discard indigenous knowledge, an important part of it survives to this day.

Tupis, Tupinambá, Guarani

Tupi is the term used to describe the people and the family of languages that includes 41 native languages spoken between Brazil, Argentina, Peru, Bolivia, Paraguay, and Uruguay. The Tupinambá people, one of the Tupi ethnic groups that lived in the Atlantic Forest in Brazil, speak a Tupi language, so researchers chose to name the people Tupinambá, and Tupi their language.

The Guarani, also living in the same countries listed above, are distinguished from the Tupinambá because they don’t speak any of the 41 languages, they speak the Guarani language. Historians believe the Guarani descended from the Tupinambá and a series of migrations changed their language over time.

Percentage of Indigenous population with national population by country in Latin America and the Caribbean (end 1990s-beginning 2000s). Credits: Raul A Montenegro and Carolyn Stephens.

In Brazil alone, there are known 220 indigenous ethnicities. The most populous group is the Guarani, approximately 46,000 people.  Anthropologists estimate that there are at least 185 isolated groups between Venezuela, Brazil, Peru, Bolívia, and Ecuador. Of these, many have their own way of looking at constellations.


Despite the many disturbing events that took place when Europeans started colonizing Brazil, records of local astronomy still exist, and they’re a good source of information for researchers. These written records provide the ‘Rosetta stone’’ that enables astronomers to translate the constellations named by the natives to the stars as we know them today.

The Tupinambá people, one of the Tupi ethnic groups that lived in the Atlantic Forest in Brazil, used to mark time according to moon phases, proving they used astronomy in their lives. The Europeans learned that as they asked the age of native Brazilians they met, the replies were large numbers, and the foreigners soon connected it to a different system of units.

Tupinambás understood the tides and their connection to the lunar phases, even without a gravitational theory. In 1612, the Franciscan missionary Claude d’Abbeville wrote that “the Tupinambá attribute the ebb and flow of the sea to the Moon and distinguish the two high tides very well that occur at the full moon and the new moon or a few days later”. It was only in 1632 that Galileu Galileiwrote in his book ‘Dialogue Concerning the Two Chief World Systems’ that the mechanism which causes the tides are Earth’s rotation and translation. It took 75 years until Isaac Newton gave the correct explanation but still lagging years behind the Tupinambás.

The seasons

Thanks to Professor Germano Afonso’s work, we learned more about Tupi astronomy in recent years. Afonso spent months among the Tupi, collecting all the information he could. He discovered that among the Tupi, the common celestial bodies used as a calendar were the Moon, the Sun, Pleiads, the galactic center, Orion and Scorpius’ region, and the Southern Cross. Their gnomon, the solar clock, called the Cuaracyraangaba, is a vertical stone pointing at the zenith, similar to many other cultures around the globe. According to local myth, the Nhanderu god created four other main gods who helped create the world. Nhanderu represents the zenith and the four gods are the cardinal points.

Indigenous solar observatory in the Mato Grosso do Sul State University.

For the Tupi, there are only two seasons: the new weather (spring and summer) and the old weather (autumn and winter) — which makes sense for a good part of the Brazilian territory in terms of climate, the four seasons system work better for mid-latitudes. Thanks to the gnomon, they knew the day on which season started depending on the Sun’s directions. This is simple, in the Southern Hemisphere, the Sun rises and sets closer to the South in the summer and closer to the north in winter.


Different from the zodiac constellations, constellations were not only patterns between stars for the indigenous people,, but also the light and dark marks in the Milky Way. Nhanderu is the best example for the dark constellations, it is the dark region near Cygnus, a northern constellation in the Milky Way plane, deriving its name from the Greek word for swan. Both the Large and Small Magellanic clouds (dwarf galaxy companions to the Milky Way) are constellations as well, both named after South American animals: Tapir’s fountain and Skunk Pig’s fountain respectively.

The Large and Small Magellanic Clouds over Paranal Observatory in Chile. Image via the European Southern Observatory.

Seasonally, the Pleiads were another tool to mark the year, they knew they would appear in a wet season and disappear in the dryer one.

The Rhea constellation. Credits: Almanaque Brasil.

The beginning of summer is based on the constellation of the Old Man marking the start of the rainy season in the North of Brazil. It is the image of a disabled person made out of some of Orion and Taurus stars. The head is in the Hyades star cluster, above the head Pleiads, Orion’s belt is in the left leg, while a shorter leg ends with Betelgeuse. He also holds a stick with his right hand to help to stand. In their mythology, the Old Man lost his right leg after he was  murdered by his wife who was younger and interested in the man’s younger brother. The gods felt sorry for him and took him to the sky in the form of a constellation.

Old Man constellation: The Old Man, in more modern vernacular, may be composed of the Hyades star cluster as his head and the belt of Orion as part of one leg. Tupi folklore relates that the other leg was cut off by his unhappy wife, causing it to end at the orange star now known as Betelgeuse. The Pleiades star cluster, on the far left, can be interpreted as a head feather. In the featured image, the hobbled Old Man is mirrored by a person posing in the foreground. Folklore of the night sky is important for many reasons, including that it records cultural heritage and documents the universality of human intelligence and imagination. Image Credit & Copyright: Rodrigo Guerra.

It’s evident that looking towards the sky is part of human nature. For Europeans, Native Americans, Aborigines, Africans, and many other cultures around the world, this was clearly a common pursuit of knowledge. The differences are the myths and shapes used alongside these observations, but the guiding principles were the same.For millennia, the sky was the best calendar we had, and it was a way to prepare for the weather ahead. Perhaps we should add a few different gods to name new planets and stars observed.