Category Archives: Astronomy

Scientists peer into the dark side of a hot Jupiter

Scientists have been looking at exoplanets for a while now, and one of the types of exoplanets that’s easiest to spot is the so-called Hot Jupiters.

Hot Jupiters are a type of planet that resembles Jupiter (they’re essentially gas giants) but they lie very close to their star — which makes them hot. But like the moon and the Earth, hot Jupiters are generally tidally locked with their star, which means one of the side is always facing the star while the other is always facing away. For the first time, researchers have looked into the dark side of a hot Jupiter.

Artist’s impression of a hot Jupiter. Image credits: Yves LC.

WASP-121 b is nearly two times the size of Jupiter and it lies so close to its star that it only takes it just 30 hours to complete a rotation. The planet was first discovered in 2015, but now, thanks to some fresh data from Hubble, astronomers can analyze it in more detail than ever before.

The planet is tidally locked, and there’s a huge temperature difference between the side that is facing towards the star and the side facing outer space. Because it’s so close to its star, even the ‘cold’ side is hot, but not nearly as hot as the star-facing side. The hot side has temperatures beyond 4,940°F (2726 °C), so hot that it breaks water molecules apart into hydrogen and oxygen. Meanwhile, the dark side has temperatures of ‘just’ 2,780°F (1526 °C), obviously still very hot, but cold enough for water molecules to form again.

The team calculated that the planet’s atmospheric movements are pushed by winds that whip the planet at whopping speeds of up to 5 kilometers per second (or more than 11,000 miles per hour).

Because there’s such a big temperature difference between the two sides, strong winds rip from one side to the other, sweeping atoms around. There’s no way water clouds (let alone liquid water) can exist on such a planet, but Hubble data shows that temperatures are low enough for metal clouds to form on the nightside. Iron and corundum (the mineral that makes up rubies and sapphires) appear to be present on the planet, and these are likely the minerals that form clouds on WASP-121 b.

This study marks the first time an exoplanet’s global atmosphere has been studied, the researchers say. The study could help us understand how the entire class of hot Jupiters forms and what implications they have for the formation of solar systems.

“We’re now moving beyond taking isolated snapshots of specific regions of exoplanet atmospheres, to study them as the 3D systems they truly are,” says Thomas Mikal-Evans, who led the study as a postdoc in MIT’s Kavli Institute for Astrophysics and Space Research.

Journal Reference: Mikal-Evans, T., Sing, D.K., Barstow, J.K. et al. Diurnal variations in the stratosphere of the ultrahot giant exoplanet WASP-121b. Nat Astron (2022). DOI: 10.1038/s41550-021-01592-w

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.

Hexagon star pattern shows James Webb is slowly getting calibrated

The James Webb telescope has completed another milestone of its journey. The so-called “Segment Image Identification” rendered one star 18 times, arranging the unfocused images into a hexagonal shape. Eventually, these 18 images will perfectly align into a single, sharp image — but for now, researchers are excited about this interim result.

This early Webb alignment image, with dots of starlight arranged in a pattern similar to the honeycomb shape of the primary mirror, is called an “image array.” Credit: NASA/STScI/J. DePasquale.

The James Webb Space Telescope’s (JWST) primary mirror, the Optical Telescope Element, consists of 18 hexagonal mirror segments made of gold-plated beryllium. Together, these mirrors combine to create a 6.5-meter (21 ft) diameter mirror — almost three times larger than Hubble’s 2.4 m (7.9 ft) mirror. But aligning them perfectly is a delicate process.

As part of this process, engineers are now using each mirror individually to create 18 unfocused copies. We’ve previously seen this happen but now, they’re organized in a shape that resembles JWST’s hexagonal mirrors.

“We steer the segment dots into this array so that they have the same relative locations as the physical mirrors,” said Matthew Lallo, systems scientist and Telescopes Branch manager at the Space Telescope Science Institute. “During global alignment and Image Stacking, this familiar arrangement gives the wavefront team an intuitive and natural way of visualizing changes in the segment spots in the context of the entire primary mirror. We can now actually watch the primary mirror slowly form into its precise, intended shape!”

A selfie taken by the James Webb telescope, showing the hexagonal arrangement of the primary mirrors. Image credits: NASA.

As Lallo mentioned, the current orientation will make it easier to further arrange and focus the mirrors. This alignment stage began on February 2 and is expected to be completed by the end of the month. After this stage, the “image stacking” stage will begin, with researchers working to bring the 18 images on top of each other into one clear, focused view. It’s expected that the telescope will become fully operational in June 2022.

It’s one of the most ambitious space missions in recent history, an “Apollo moment” that will fundamentally alter our understanding of the universe, NASA says.

James Webb is expected to offer researchers an unprecedented view of the universe, focusing on four main objectives:

  • light coming from the very first stars and galaxies that formed after the big bang;
  • galaxy formation and evolution;
  • star formation and planet formation;
  • planetary systems and the origins of life.

We expect the first images and studies to come in from JWST later this year.

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.

Researchers have just found the biggest galaxy ever discovered — and it’s big alright

The distance from the Sun to Pluto, the farthest planet(oid), is 0.000628 light-years. The closest solar system to us, Alpha Centauri, is 4.2 light-years away. The Milky Way Galaxy is 52,850 light-years across. But Alcyoneus, the newly-discovered galaxy, is a whopping 16.3 million light-years wide.

Giant radio galaxies (GRGs, or just ‘giants’) are the Universe’s largest structures generated by individual galaxies. They were first discovered accidentally by wartime radar engineers in the 1940s, but it took over a decade to truly understand what they were — with the aid of radio astronomy. Radio astronomy is a subfield of astronomy that studies celestial objects using radio frequencies.

These giants dominate the night sky with their radio frequency signals (astronomers use different types of frequencies to study the universe). They generally consist of a host galaxy — a cluster of stars orbiting a bright galactic nucleus containing a black hole — and some colossal jets or lobes that erupt from this galactic center.

Most commonly, radio galaxies have two elongated, fairly symmetrical lobes. These radio lobes are pretty common across many galaxies — even the Milky Way has them — but for some reason, in some galaxies, the lobes grow to be immensely long. Discovering new radio galaxies could help us understand these processes — this is where the new study comes in.

Researchers led by astronomer Martijn Oei of Leiden Observatory in the Netherlands have discovered the largest single structure of galactic origin. They used the LOw Frequency ARray (LOFAR) in Europe, a network of over 20,000 radio antennas distributed across Europe.

“If there exist host galaxy characteristics that are an important cause for giant radio galaxy growth, then the hosts of the largest giant radio galaxies are likely to possess them,” the researchers explain in their preprint paper, which has been accepted for publication in Astronomy & Astrophysics.

The lobes of the newly-discovered galaxy. Image credits: Oei et al (2022).

According to the authors, this is the most detailed search ever of radio galaxy lobes, and lo and behold, the results also came in.

Alcyoneus lies some 3 billion light-years away from us, a distance that’s hard to even contemplate (though it’s not nearly the farthest object we’ve found, which lies over 13 billion light-years away). Its host galaxy appears to be a fairly normal elliptical galaxy. In fact, it almost seems too inconspicuous.

But even this could tell us something: you don’t need a particularly large galaxy or a particularly massive black hole at its center to create a radio galaxy.

“Beyond geometry, Alcyoneus and its host are suspiciously ordinary: the total low-frequency luminosity density, stellar mass and supermassive black hole mass are all lower than, though similar to, those of the medial giant radio galaxies,” the researchers write.

“Thus, very massive galaxies or central black holes are not necessary to grow large giants, and, if the observed state is representative of the source over its lifetime, neither is high radio power.”

The study has been published in arXiv.

New planet found “next door” to our solar system

At one quarter the mass of the Earth, the newly-discovered planet is not only one of the closest planets we know of, but also one of the lightest. The planet is named Proxima d.

Artist’s impression of the newly-discovered planet. Image credits: Credit: ESO/L. Calçada.

Hey planet, here’s an ESPRESSO

In 1915, the Scottish astronomer Robert Innes discovered a new star. He called it Proxima Centauri (or rather, Proxima Centaurus).

Proxima Centauri is the closest star to Earth, lying just over four light-years away — and will continue to be so for about 25,000 years, after which Alpha Centauri A and Alpha Centauri B will move closer to our solar system and will take alternating turns as the “closest star to Earth” (for about 80 years each).

But it took another hundred years after the star was named for the first planet in the Proxima Centauri solar system to be discovered. Astronomers are nothing if not methodical, so in 2016, when they discovered a planet, they called it Proxima b. They found another planet candidate in 2019 which they called Proxima c. Now, they’ve discovered a new planet and named it (you’ve guessed it) Proxima d.

“The discovery shows that our closest stellar neighbor seems to be packed with interesting new worlds, within reach of further study and future exploration,” explains João Faria, a researcher at the Instituto de Astrofísica e Ciências do Espaço, Portugal and lead author of the study published today in Astronomy & Astrophysics.

The planet was first discovered in 2020, and was now confirmed with the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO).

“After obtaining new observations, we were able to confirm this signal as a new planet candidate,” Faria says. “I was excited by the challenge of detecting such a small signal and, by doing so, discovering an exoplanet so close to Earth.”  

The planet was discovered using a less common method. Because planets don’t emit their own light, researchers rely on indirect information to find them. Most commonly, they use a method called the transit method — basically, they measure the luminosity coming from a star and look for dips in luminosity caused by planets passing in front of that star. But Proxima d was discovered using the radial velocity technique.

The technique works by detecting tiny wobbles in the motion of the star — wobbles created by a planet’s gravitational pull. With this, they can not only detect the presence of a star but also calculate its mass.

A depiction of the radial velocity method showing how a smaller object (such as an extrasolar planet) orbiting a larger object (such as a star) could produce changes in position and velocity of the latter as they orbit their common center of mass (red cross). Image via Wiki Commons.

“This achievement is extremely important,” says Pedro Figueira, ESPRESSO instrument scientist at ESO in Chile. “It shows that the radial velocity technique has the potential to unveil a population of light planets, like our own, that are expected to be the most abundant in our galaxy and that can potentially host life as we know it.”

“This result clearly shows what ESPRESSO is capable of and makes me wonder about what it will be able to find in the future,” Faria adds.

The gravitational effect of Proxima d is pretty small — it only causes Proxima Centauri to wobble by around 40 centimeters per second (1.44 km/hour) — and it’s striking that astronomers can detect these small differences from 4 light-years away. Based on this, researchers calculated that the planet is around one-quarter the mass of the Earth and one of the lightest exoplanets ever found.

This image of the sky around the bright star Alpha Centauri AB also shows the much fainter red dwarf star, Proxima Centauri, the closest star to the Solar System. The picture was created from pictures forming part of the Digitized Sky Survey 2. The blue halo around Alpha Centauri AB is an artifact of the photographic process, the star is really pale yellow in color like the Sun. Image credits: Digitized Sky Survey 2. Acknowledgment: Davide De Martin/Mahdi Zamani.

The planet does not lie in the habitable zone. Although the star is a red dwarf star with a mass around 8 times lower than that of the Sun, the planet simply orbits the star too closely. Assuming an Earth-like reflectivity of the planet, the surface temperature would be 87 °C (188 °F) — too hot to support life as we know it. Another Proxima Centauri planet (Proxima b) could lie in the habitable zone, but this is still disputed by astronomers.

Researchers expect more intriguing data to come from ESPRESSO’s search for other worlds, especially as it will soon be complemented by ESO’s Extremely Large Telescope (ELT), currently under construction in the Atacama Desert. Together, these two will enable researchers to discover and study many more planets around nearby stars.

The study was published in the journal Astronomy and Astrophysics.

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.

Hubble spots three galaxies dancing in epic photo

The two galaxies in the upper-right part of the image seem to be interacting with each other — potentially even merging.

NGC 7764A lies some 425 million light-years from Earth, in the constellation Phoenix, first described 400 years ago, on a celestial atlas called Uranometria. Although it’s so far away, Hubble was able to snap this image using both its Advanced Camera for Surveys (installed in 2002) and Wide Field Camera 3 (the most technologically advanced visible-light camera on Hubble, installed in 2009). Both are advanced systems designed to capture images deep in space.

The two right-side galaxies appear to be dancing around each other — a dance that is also potentially affected by the bowling-ball shaped galaxy on the right side of the picture. It’s not uncommon for galaxies to interact and even collide, although this process happens very slowly, and is not technically a collision (since galaxies have more empty space than stars and planets), but rather gravitational interactions between the components that make up the two galaxies. Colliding may cause the two galaxies to merge, if they don’t have enough momentum to continue traveling after the collision. When this happens, the two galaxies eventually fall back on each other and merge into one galaxy. When galaxies just pass through each other without merging, they mostly retain their material and overall shape.

It’s not clear which of these processes is going on here, or if there’s another process altogether — although a head-on collision appears unlikely. As NASA explains, the galaxy in the lower left may also be involved, given that it is relatively close. The European Space Agency (ESA) also seems pretty stoked about the shape the two galaxies are making as they interact.

“By happy coincidence, the collective interaction between these galaxies has caused the two on the upper right to form a shape, which from our solar system’s perspective, resembles the starship known as the USS Enterprise from Star Trek,” an ESA text notes.

The space agency also points out just how clunky the naming of these galaxies is. The three galaxies are called NGC 7764A1, NGC 7764A2, and NGC 7764A3, respectively. Astronomers need these complex but specific names to make sure they know exactly what object they’re talking about and prevent any confusion.

“This rather haphazard naming makes more sense when we consider that many astronomical catalogs were compiled well over 100 years ago, long before modern technology made standardizing scientific terminology much easier,” the article adds.

“As it is, many astronomical objects have several different names, or might have names that are so similar to other objects’ names that they cause confusion.”

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).

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.

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.

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.

You can now hold the whole (simulated) universe in the palm of your hand

A team of international researchers led by members at the National Institutes of Natural Sciences in Tokyo wants to put the universe in the palm of your hand.

Image credits IAA-CSIC.

The Universe is a really big place, which can make understanding it a bit difficult. What would definitely help in this regard would be a simulation encompassing it in its entirety — which is exactly what the researchers did. Named Uchuu (“Outer Space” in Japanese), this is the largest and most realistic simulation of the Universe to date, consisting of 2.1 trillion particles spread across a simulated cube whose side is 9.63 billion light-years.

A digital new world

The simulated universe is the product of a collaboration between researchers from Japan, Spain, the U.S.A., Argentina, Australia, Chile, France, and Italy. ATERUI II, the most powerful supercomputer dedicated to astronomy in the world, was used to produce Uchuu, an effort that still took a full year.

“To produce Uchuu we have used […] all 40,200 processors (CPU cores) available exclusively for 48 hours each month. Twenty million supercomputer hours were consumed, and 3 Petabytes of data were generated, the equivalent of 894,784,853 pictures from a 12-megapixel cell phone,” explains Tomoaki Ishiyama, an associate professor at Chiba University who developed the code used to generate Uchuu.

The intended purpose behind Uchuu is to give astronomers a new tool to understand the results of Big Data galaxy surveys. This type of research simply generates immense quantities of data and making heads and tails of it all can become quite difficult.

But Uchuu’s sheer scale can, counterintuitively, help researchers parse this data much more easily. The side of the simulated square, of 9.63 billion light-years, is around three-quarters of the estimated distance between the Earth and the farthest galaxies we can currently observe. This provides the context for researchers to study the evolutionary history of the Universe on a scale that was previously impossible.

Obviously, the software isn’t perfect, nor does it simulate an entire Universe in complete detail. It focuses on the large-scale structures that defined its history and evolution. The team explains that they focused on the large-scale structures formed by dark matter (known as ‘halos’) which control processes such as the formation of galaxies, instead of relatively smaller structures such as stars.

This focus on the large scale comes down to technical constraints. Uchuu aims to simulate almost 13.8 billion years of the history of the Universe, roughly from the Big Bang up to today.

“Uchuu is like a time machine: we can go forward, backward and stop in time, we can ‘zoom in’ on a single galaxy or ‘zoom out’ to visualize a whole cluster, we can see what is really happening at every instant and in every place of the Universe from its earliest days to the present, being an essential tool to study the Cosmos,” explains Julia F. Ereza, a Ph.D. student at the Institute of Astrophysics of Andalusia (Instituto de Astrofísica de Andalucía / IAA-CSIC), who uses Uchuu for their research.

The end of this process is, essentially, a recording of all the computations ATERUI II performed during this time. This shows the evolution of dark matter haloes in a 100-terabyte catalog, one which you can download and browse at your own leisure — if you have the disk space to spare, which most of us here don’t.

But fear not! The catalog is also publically available on the cloud thanks to the IAA-CSIC (link at the bottom of the page). Future releases will include catalogues of virtual galaxies and gravitational lensing maps.

Neutron Stars: one of the most extreme objects we know

Neutron stars are one of the most amazing things we know of in the universe. A teaspoon of neutron star material would weigh around a billion tons, making them some of the densest objects in the universe, second only to black holes. Aside from being extremely dense, they can emit bizarre pulses, and sometimes, they form in binary systems — where things can get even wilder.

The gas comprising the disk orbits around and gradually spirals onto the neutron star. Credits: Wagoner (2003).

In 1969, Jocelyn Bell detected the first neutron star. She was a PhD student at Cambridge University and detected a very powerful and extremely regular radio pulse (which was later named a pulsar). It was so eerily regular that the signal’s first nickname was LGM-1, “Little Green Men 1”.

The people who later got involved in the study didn’t really believe it was another civilization and set out to find the signal’s underlying cause. They found it to be a neutron star, the collapsed core of a massive supergiant star that wasn’t quite massive enough to turn into a black hole.

Today, we can detect neutron stars by looking at their signals with X-ray detectors, and we’ve learned quite a lot about them.


Neutron stars are born when a star with 8 to 20 solar masses runs out of fuel. The star undergoes a number of nuclear fusion reactions which leave behind a layered onion shape, including a core made of iron. The iron core is the key to how the star will develop; if the core’s mass is above a limit (called the Chandrasekhar limit), the star will collapse into a neutron star or black hole. Stars with masses lower than this limit will remain stable as white dwarfs.

The formation of a neutron star can happen at dazzling speed. A supernova occurs within 0.1 seconds and what is left behind from the primary star is just its core, which is now made out of neutrons. The explosion releases neutrinos which are antisocial particles that don’t interact with almost any other particles.

A neutron star begins its life as a star between about 7 and 20 times the mass of the sun. When this type of star runs out of fuel, it collapses under its own weight, crushing its core and triggering a supernova explosion. What remains is an ultra-dense sphere only about the size of a city across, but with up to twice the mass of the sun squeezed inside. Credits: NASA/NICER.

In 1987, a supernova exploded and we detected neutrinos from outside of the solar system for the first time in the Kamiokande detector. 

The neutron star left from the colossal boom has nearly 1.5 solar masses, but its radius is just around 10 kilometres, making it the densest star in the universe we know of –  one tablespoon of a neutron star contains billions of kilograms. Mostly made of neutrons, of course, but also with some protons and electrons here and there, without the extra particles it wouldn’t be stable enough, the neutrons could decay into protons and electrons.

Interestingly though, neutron stars don’t collapse on themselves despite their massive gravitational attraction and are generally stable.

This happens because neutrons are essentially fermions, subatomic particles that respect their own personal space; you could say they practice subatomic social distancing.

In more scientific terms, fermions obey the Pauli exclusion principle: “you can’t have identical fermions in the same quantum state”. This means the identical neutrons can’t occupy the same space, thus, the pressure from ‘trying to avoid other neutrons’ personal space’ competes against gravity and the neutron star keeps itself stable for a long time. This type of matter is often referred to as “degenerate matter” — a highly dense state of fermionic matter in which the Pauli exclusion principle exerts enough pressure (in addition to, or in lieu of thermal pressure) so that the neutron star doesn’t collapse.

Classifying neutrons stars

There are several ways to classify neutron stars, but commonly, there are three types of neutron stars.

The easiest ones to find are the pulsars. Pulsars are highly magnetized rotating neutron stars that emit beams of electromagnetic radiation from their magnetic poles. They have a highly periodic pulse, which can repeat a cycle within milliseconds or over several seconds. The rotation and the beam don’t necessarily need to be aligned, that’s why most images illustrating pulsars show the tilted version of the cycles.

Credits: NASA/JPL-Caltech.

Pulsars are very serious about their timing — so much so that astronomers sometimes use them as celestial timekeepers. The timing from their pulses can be used to precisely find objects, just like how sailors of yore used stars to guide themselves at sea. The Voyager spacecraft has a message to any civilization to find Earth. How did they map it? With radio pulsars. The positions of galactic pulsars are placed on a scale in the map with their number of rotations per cycle dashed along the lines.

Another neutron star is the magnetar, and here, things really get extreme. Pulsars are already extreme objects with titanic magnetic fields, but the magnetars have fields 1000 stronger than even that of a pulsar. To get an idea of how big a field we’re talking about, the Large Hadron Collider has magnets to help accelerate particles, and its magnetic field is around 8.3 Tesla. Magnetar’s magnetic field is 10,000,000 billion Tesla. They can also cause giant flares, and release energy 100,000,000 billion times stronger than a solar flare.


Neutron stars can orbit a companion, sometimes a white dwarf, sometimes a main-sequence star, or even another neutron star. Things get weird when they start to merge. 

This animation captures phenomena observed over the course of nine days following the neutron star merger known as GW170817. They include gravitational waves (pale arcs), a near-light-speed jet that produced gamma rays (magenta), expanding debris from a kilonova that produced ultraviolet (violet), optical and infrared (blue-white to red) emission, and, once the jet directed toward us expanded into our view from Earth, X-rays (blue).
Credits: NASA’s Goddard Space Flight Center/CI Lab
Download this video in HD formats from NASA Goddard’s Scientific Visualization Studio

On 2017 August 17, both the Virgo and Laser Interferometer Gravitational-Wave Observatory (LIGO) teams detected two neutron stars merging gravitational waves in another galaxy called the GW170817. Because the merging process was so catastrophic, the event emitted gamma rays detected by the Fermi Gamma-ray Space Telescope. There were also visual signals from that event and other important measurements, multi-messenger observations, something widely anticipated as the future of astrophysics.


Remember the Pauli exclusion principle? Well, we’re not done with it just yet. There is a phase of matter which is like a fluid but not really, and it works in the same way as the superconductors.

This stylized animation shows the structure of a neutron star. The states of matter within neutron stars’ inner cores remains a mystery.
NICER will confront nuclear physics theory with unique measurements, exploring the exotic states of matter within neutron stars through rotation-resolved X-ray spectroscopy. Credits: NASA/Nicer.

When you try to join particles with the same charge they repel each other. But at a very specific temperature and in the case of neutron stars, density, they can get along and ignore the social distancing. Superconductors have a weird mechanism to form interactions between electrons, the Cooper pairs. These interactions make the superconductor have zero resistivity, for a superfluid, it means zero viscosity, a property in fluids that make them flow slowly. 

Neutrons aren’t supposed to form pairs either, even though they aren’t charged. However, in that extreme environment, they manage to form this superconducting phase that is actually called a superfluid state. It happens inside the neutron star’s inner crust and outer core.

The Cooper pairs made of neutrons make a superfluid state possible in a neutron star. It may sound weird to call it fluid in such a dense object, but if you think about it is not a problem, everything is dense, and the core is denser, a less dense region compared to a super dense one can be called a fluid.

The evidence for that is the result of the pairing. The relationships between neutrons aren’t stable so they break up and emit neutrinos in response, this neutrino release makes the star cool down. Two groups independently detected the cooling mechanism from the neutron star inside the Cassiopeia A. The 10-year observation shows that the star cooled 4%, the best explanation is that it agrees with the superfluid theory. 

Cassiopeia A. Image credit: NASA/CXC/SAO.

That was just a few of the quirky characteristics of neutron stars, they can get weirder than that. Exotic stuff probably happens in their inner cores, explained with more quantum mechanics which could make ‘Rick and Morty’ seem old hat.

All-female team highlights mysteries from a peculiar solar storm

Like meteorologists give first names to tropical cyclones, solar events (especially strong ones) are also named — but they’re given names based on their dates. Also like cyclones, some solar storms are more famous than others.

The Halloween Storms of 2003, for instance, are among these famous ones. They created auroras at lower latitudes than expected. On March 8, 2019, a peculiar solar storm formed; it was named the 2019 International Women’s Day event. Now, a team has found even more weird things about the storm.

2019-03-08 AIA composite 211, 193, 171. Courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.

Space weather events are famous for the impressive amount of energy released in the solar system. Coronal Mass Ejections (CME) happen when the Sun releases plasma from a strong magnetic field. Some CMEs are associated with solar flares which are solar activities connected to the 11-year solar cycle.

During solar maximums, more solar flares occur — and since they can trigger geomagnetic storms that can disable satellites and knock out electric power grids, researchers are following them closely. This one was unusual from the start.

“This solar storm seemed peculiar from the very first moment. It had many accompanying phenomena that could be observed at the Sun, something that is usual for very strong solar storms. The only trouble was — the storm was not strong at all!”

says Dr. Mateja Dumbović, the lead author of the study and a research associate at Hvar Observatory in Croatia.

Solar flares are rated from weak to strong (A, B, C, M, and X). The X-class flares, the strongest of the bunch, are powerful enough to power 1.2 billion Saturn V rockets — enough energy to explore the entire solar system. In the 2019 event, the storm was C-class, not extremely strong. However, solar activity that usually comes with stronger flares was observed.

After the flare, two Extreme Ultraviolet (EUV) waves were registered during the event. These are dangerous phenomena which can weaken the Earth’s magnetic field. As the Sun was emitting all that energy, a ‘hole’ of power is left behind, it is called a coronal dimming. 

In the International Women’s Day event, type II and III radio bursts were present. Radioactivity is the usual concern with space weather because of potential interference with satellites, especially those related to georeference. Every time a strong CME is happening, intense radio emissions can be detected, this is called radio burst. 

Usually, unlike the International Women’s Day event, space weather can bring us beautiful auroras, but life is not a bed of roses. Events like this are rare, but when they occur they can cause serious problems for us.

The study was published in Astronomy & Astrophysics.