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.
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.”
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.
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.”
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.
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.
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.
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.
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.
Researchers at CHIME, the Canadian Hydrogen Intensity Mapping Experiment, report seeing over 500 fast radio bursts between (FRBs) 2018 and 2019. Such signals are believed to reach Earth from other solar systems.
FRBs are intense bursts of radio waves that pulse, generally, for fractions of a millisecond at a time. We don’t exactly know what creates them, why, or how, but we do know they come from outside of our planet. One possible explanation is that they’re created by neutron stars, some hundreds of millions of light years away, as they spin.
Still, we’ve only discovered FRBs in 2007. The observations from CHIME are helping us better understand what they are, and might even help answer the questions everyone holds in the back of their minds: are we seeing alien activity?
Bursting with radio
“With all these sources, we can really start getting a picture of what FRBs look like as a whole, what astrophysics might be driving these events, and how they can be used to study the universe going forward,” said Kaitlyn Shin, CHIME member and a graduate student in the Massachusetts Institute of Technology’s Department of Physics, in a statement.
CHIME has been a boon for the research of these radio signals — before it was established, there were less than 100 confirmed FRBs observations. But after only one year’s worth of observations, the project has uncovered hundreds more.
Data from the CHIME project seems to indicate that as many as 800 such events pass through the sky every day, most likely from neutron stars scattered around the galaxy. Most of them are evenly distributed in space, single-burst events that don’t seem to repeat.
But at least 61 FBR signals were recorded originating from the same 18 sources.
It’s far too early to speculate on what — if anything — these signals mean. There are natural processes we know of that can create them, and given the distances involved when talking about outer space, only catching glimpses of these signals, milliseconds-long, isn’t very surprising. Even seeing them repeating from the same source isn’t that surprising; unlikely, but not that surprising.
Naturally, however, it raises the possibility of alien activity. Natural events could create these FBRs, but so could a sufficiently-advanced civilization. It’s not something we can say for certain, far from it, but it is within the realm of possibility.
The CHIME telescope is an outlier among radio telescopes. It’s composed of an array of four large antennas which are entirely motionless. It relies on the rotation of the Earth alone to sweep across the sky and receive incoming radio signals. Instead of moving its dishes to capture radio waves from different areas of the sky, CHIME employs an “all digital design” for the role. The signals it receives are fed through a correlator which processes them, allowing the team to know which direction they come from. In essence, this allows CHIME to look in a thousand directions at once. On an average day, CHIME processes around 7 terabits of data per second.
Astronomers have detected a new, potentially deadly emanation coming from Uranus: X-rays. While most of these are likely produced by the sun and then reflected by the blue planet, the team is excited about the possibility of a local source of X-rays adding to these emissions.
The seventh planet from the sun has the distinction of being our only neighbor that rotates on its side. But that’s not the only secret this blue, frigid dot in space seems to hide, according to new research. The planet also seems to be radioactive — after a fashion. This discovery currently leaves us with more questions than answers, but it could help us better understand Uranus in the long run.
Deep space rays
Since it’s so far away, we’ve had precious few opportunities to interact with the planet. In fact, the only human spacecraft to ever come near Uranus was Voyager 2, and that happened in 1986. So most of our data regarding the frozen giant comes from telescopes, such as NASA’s Chandra X-ray Observatory and the Hubble Space Telescope.
A new study based on snapshots of Uranus taken by Chandra in 2002 and 2017. These revealed the existence of X-rays in the data from 2002, and a possible burst of the same type of radiation in the second data set. The 2017 dataset was recorded when the planet was approximately at the same orientation relative to Earth as it was in 2002.
The team explains that the source of these X-rays, or at least the chief part of them, is likely the Sun. This wouldn’t be unprecedented: both Jupiter and Saturn are known to behave the same way, scattering light from the Sun (including X-rays) back into the void. Earth’s atmosphere, actually, behaves in a similar way.
But, while the team was expecting to observe X-rays coming off of Uranus due to these precedents, what really surprised them is the possibility that another source of radiation could be present. While still unconfirmed, such a source would have important implications for our understanding of the planet.
One possible source would be the rings of Uranus; we know from our observations of Saturn that planetary ring systems can emit X-rays, produced by collisions between them and charged particles around the planets. Uranus’ auroras are another contender, as we have registered emissions coming from them on other wavelengths. These auroras are also produced by interactions with charged particles, much like the northern lights on Earth. Auroras are also known to emit X-rays both on Earth and other planets.
The piece that’s missing in the aurora picture, however, is that researchers don’t understand what causes them on Uranus.
Its unique magnetic field and rapid rotation could create unusually complex auroras, the team explains, which further muddies our ability to interpret the current findings; there are too many unknown variables in this equation. Hopefully, however, the current findings will help point us towards the answers we need.
The paper “A Low Signal Detection of X‐Rays From Uranus” has been published in the Journal of Geophysical Research: Space Physics.
It’s one of the greatest scientific projects of the century and it just got the official green light. The Square Kilometre Array Observatory (SKAO) will be the largest and most complex radio telescope network in the world, with an estimated of cost $2.2 billion. Once built, it will offer us an unprecedented view of the universe.
The building initiative has 14 member countries and around 100 organizations spread across about 20 countries, all of which had their first meeting which was done online because of the coronavirus pandemic. SKAO has been discussed for over 30 years so the fact that it’s finally moving forward is a big deal, and not just for astronomers.
The telescope will have unprecedented sensitivity and it will pick up any extra-terrestrial transmissions. This could help astronomers answer important questions, from whether we are alone in the universe to what’s dark energy, an unknown form of energy that appears to be driving the cosmos apart at an accelerating rate
“Today marks the birth of a new observatory,” Phil Diamond, appointed first Director-General of SKAO, said in a statement. “And not just any observatory – this is one of the mega-science facilities of the 21st century. It is the culmination of many years of work. This is about participating in one of the great scientific adventures of the coming decades.”
At their first meeting, SKAO’s council approved a whole series of policies, regulations, and procedures that will make the observatory real — the boring, but very important things. But the key step is actually building the actual telescope. Member countries hope to send invitations to tender to the industry from July onwards, with the entire construction expected to be finished in about a decade.
The project is so astonishing in scope that it includes setting up radio receivers in two continents, far away from any machine that emits radio waves. One location will be the Karoo in South Africa’s Northern Cape, where 197 parabolic radio antennae, or dishes, will be built. The South African Radio Astronomy Observatory (SARAO) has already built 64 of them.
The other part of the project will be located in the Western Australian outback at Murchison. An impressive two meters tall low-frequency aperture array telescopes will be built there. Alongside the dishes in South Africa, this will create a collecting area spanning across two continents that allow the detection of very faint radio signals.
Blade Nzimande, Minister of Higher Education, Science & Innovation of South Africa, a member of SKAO, said in a statement: “The SKA project will act as a catalyst for science, technology and engineering innovation, providing commercial opportunities to local high-tech industry, and creating the potential to put Africa on the map as a global science and innovation partner.”
The council meeting that kicked off the project was led by the countries that have ratified the SKA treaty. These are Australia and South Africa, as the telescope’s host nations; Italy, the Netherlands, Portugal; and the United Kingdom, which is where the organization has its headquarters at the Jodrell Bank radio observatory. Other countries joined the meeting as observers.
The financing for the project is coming from all the member countries. They estimate construction and operation will consume about $2.4 billion over the next decade. It will be by far the largest radio telescope array ever constructed, with a total collecting area of well over one square kilometer. We’ll have to wait a few years to see it, but the results could be quite significant.
Mothballed on NASA’s shelves were the plans to view stars 13 billion years in the past. Now, a group of astronomers from the University of Texas at Austin want to dust off ideas for a moon-based telescope and try to put them to good use.
The project was first tabled more than a decade ago because we just didn’t have enough science on the earliest stars at that point. It was initially coined the Lunar Liquid-Mirror Telescope (LLMT) when it was first proposed in 2008 by a team at the University of Arizona, and it would feature a liquid mirror telescope operating from the surface of the Moon, far away from any light pollution.
The proposed telescope, nicknamed the “Ultimately Large Telescope” by NASA Hubble Fellow and lead researcher Anna Schauer, would have a mirror 100 meters (300 feet) in diameter. It would operate autonomously from the lunar surface, receiving power from a solar power collection station on the moon relaying data to a satellite in lunar orbit, and from there, to Earth.
While the technology does not currently exist for such a device, and it would admittedly be very expensive, astronomers say the cost would be worth it (though the government might sing a different tune).
“Throughout the history of astronomy, telescopes have become more powerful, allowing us to probe sources from successively earlier cosmic times—ever closer to the Big Bang,” said professor and team member Volker Bromm, a theorist who has studied the first stars for decades. “The upcoming James Webb Space Telescope (JWST) will reach the time when galaxies first formed. But theory predicts that there was an even earlier time, when galaxies did not yet exist, but where individual stars first formed—the elusive Population III stars. This moment of ‘very first light’ is beyond the capabilities even of the powerful JWST, and instead needs an ‘ultimate’ telescope.”
Pop III stars, as they are somtimes called by astronomers, are composed entirely of primordial gas — helium, hydrogen, and very minute amounts of lithium and beryllium. This means that the gas from which these stars formed had not been ‘recycled’ (incorporated into, and then expelled) from previous generations of stars, but was pristine material left over from the Big Bang.
Pop III stars are likely tens or 100 times larger than the Sun. They’re a class of giant, hot, and luminous stars thought to have existed in the primordial days of the universe. However, while researchers now strongly suspect that they do exist, we’ve never actually seen one — which is why the Ultimate Telescope would be useful.
Rather than coated glass, the telescope’s mirror would be made of liquid, as it’s lighter, and thus cheaper, to transport to the Moon. It would also be a spinning vat of liquid, topped by a metallic – and thus reflective – liquid (previous liquid mirror telescopes have used mercury). The vat would spin continuously, to keep the surface of the liquid in the correct paraboloid shape to work as a mirror.
The position of the telescope would be stationary, situated inside a crater at the Moon’s north or south pole. In order to study the first stars, the Ultimately Large Telescope would stare at the same patch of sky continuously, to collect as much light from them as possible.
“This moment of first light lies beyond the capabilities of current or near-future telescopes. It is therefore important to think about the ‘ultimate’ telescope, one that is capable of directly observing those elusive first stars at the edge of time.”
The telescope proposal will be published in an upcoming issue of The Astrophysical Journal.
New images captured by the GREGOR telescope in Tenerife, Spain, are giving us an unique view of the surface of the sun.
These are the highest-resolution images of our host star ever taken by a European telescope, according to the authors. The results definitely support that claim — they give us a stunning look at the shapes and movements of solar plasma and the eerie dark voids of sunspots.
Although GREGOR has been in operation since 2012, it underwent a major redesign this year and also suffered a temporary pause in activity due to the pandemic. Now it’s up and running again, and its new, improved systems allow it to spot details as small as 50 kilometers in size on the solar surface. It might not sound like much, but this is the highest resolution of any European telescope (and, relative to the sun’s diameter of 1.4 million kilometers, quite good).
“This was a very exciting but also extremely challenging project,” said Lucia Kleint, who led the upgrade efforts on GREGOR. “In only one year we completely redesigned the optics, mechanics, and electronics to achieve the best possible image quality.”
To give you an idea of the telescope’s new abilities, she describes the images it captured as “if one saw a needle on a soccer field perfectly sharp from a distance of one kilometer”.
The sun isn’t a solid object with a static, solid contour. Rather, its surface is always roiling and churning with super-heated plasma. The new images from GREGOR show the twisting structures created on the star’s surface and the contrasting darkness of sunspots. Sunspots are areas on the solar surface where magnetic fields are extremely strong, generating a spike in local pressure which darkens the area.
Time is running out to catch a glimpse of the comet NEOWISE. The comet — the brightest object to grace the skies over the Northern Hemisphere in 25 years — will soon disappear from view. At least as far as the naked eye is concerned. Fortunately, the Hubble Space Telescope is on hand to capture stunning images of the comet — discovered on March 27th by NASA’s Wide-field Infrared Survey Explorer (WISE) space telescope during its mission to search for near-Earth objects.
The image taken by Hubble on 8th August — which represents the closest ever taken of the comet since it first lit up the sky — shows NEOWISE as it sweeps past the Sun. This is the first time that astronomers have managed to capture such a bright object as it passes our star.
Hubble snapped the object as it rapidly makes its way out of the solar system, with it not scheduled to return for 6,800 years. The comet caused a stir amongst amateur star watchers and the general public as it was visible with the naked eye under the right conditions.
“Nothing captures the imagination better than actually seeing its tails stretching into the sky in person,” Qicheng Zhang, a graduate student studying planetary science at Caltech, Pasadena, CA, who has been heavily involved in the study of NEOWISE. “The comet last came around about 4,500 years ago. This was around when the Egyptian pyramids were being built.”
“My research area covers comets and their evolution under solar heating,” Zhang explains to ZME Science. “I also like to keep track of potentially bright comets to actually see in the sky, which included this particular comet.”
The image shows NEOWISE’s halo of glowing gas and dust illuminated by light from the Sun surrounding the icy nucleus of the comet, too small at little more than 4.8km across to be fully resolved by the telescope. In contrast, the dust halo that surrounds the comet’s heart is too large to be fully resolved by the space telescope, with its diameter measuring an estimated 18,000 km.
Zhang points out that as NEOWISE moves past the Sun, there is a chance we could still glimpse its icy core: “As the comet recedes from the Sun, the dust with clear and reveal the solid nucleus currently buried within, providing an opportunity to directly observe the source of all the activity that made the comet impressive last month.”
Let’s Stick Together: Why NEOWISE Survived and ATLAS Didn’t
Previous attempts to capture other bright comets as they pass the Sun have failed because these objects have disintegrated as they passed too close to the star. This break-up is driven by both the incredible heat of the Sun causing the icy heart of the comets to fragment, and the powerful gravitational influence of our star further pulling the comets apart.
The most striking example of this came shortly after the discovery of NEOWISE, with the observation of the fragmentation of the comet ATLAS in April this year. The collapse of this comet — believed at the time to offer our best look at such an icy body — in 30 separate pieces was also caught by Hubble.
Unlike comet ATLAS, itself only discovered in December 2019, comet NEOWISE somehow survived its close passage to the Sun–with its solid, icy nucleus able to withstand the blistering heat of the star– enabling Hubble to capture the comet in an intact state.
As the latest image of NEOWISE shows, however, it is not going to escape its encounter with the Sun completely unscathed. Jets can clearly be seen blasting out in opposite directions from the poles of the comet’s icy nucleus. These jets represent material being sublimated–turning straight from a solid to a gas skipping a liquid stage–beneath the surface of the comet. This ultimately results in cones of gas and dust erupting from the comet, broadening out as the move away from the main body, forming an almost fan-like shape.
Far from being just a stunning image of a comet as it passes through the inner solar system, the Hubble images stand to teach astronomers much about NEOWISE and about comets in general.
“It’s a fairly large comet that approached closer to the Sun than the vast majority of comets of its size do,” Zhangs says. “These factors contributed to its high brightness and also made it a good candidate to see how solar heating alters comets, as the effects are theoretically amplified by its close approach to the Sun.
“That information is useful for interpreting observed characteristics of other comets that don’t approach as close to the Sun, and thus where the changes are more gradual and might not be directly observable.”
In particular, the colour of the comet’s dust halo, and the way it changes as NEOWISE moves away from the Sun, gives researchers a hint as to the effect of heat on such materials. This could, in-turn, help better determine the properties of the dust and gas that form what is known as the ‘coma’ around a comet.
“We took images to show the colour and polarization of the dust released by the comet, to get a sense of what it looks like before it’s broken down by sunlight,” says Zhang. “That analysis is ongoing–and will take a while to do properly–but as the published images show, we’ve caught at least a couple of jets carrying dust out from the rotating nucleus.”
The information contained in the Hubble data will become clearer as researchers delve deeper into it. But, the investigation of NEOWISE’s cometary counterparts will benefit from future telescope technological breakthroughs. This will include spotting comets much more quickly and thus, further out from the Sun.
“When this comet was discovered by the NEOWISE mission, it was only 3 months from its close approach to the Sun and had already begun ramping up activity,” Zhang says. “More sensitive surveys, like the upcoming Legacy Survey of Space and Time (LSST) at the Rubin Observatory, will allow us to find such comets much earlier before they become active, enabling us to track them throughout their apparition from beginning to end.
“This will facilitate a more precise comparison of what changes the comets undergo during their solar encounter.”
The next step in Zhang’s research, however, will be comparing the qualities of comet NEOWISE to other such objects, particularly a recent interstellar visitor to our solar system: “This is one of three comets I have observed or have planned to observe in this manner, the others being the interstellar comet 2I/Borisov and the distant solar system comet C/2017 K2 (PANSTARRS),” the researcher concludes. “My team of collaborators and I will be evaluating all three comets to see how their differences in present location and formation/dynamical history translate into differences in physical properties.”
The Arecibo Observatory in Puerto Rico, one of the largest radio telescopes in the world, was severely damaged during a tropical storm, with problems starting from a broken cable.
This is just the latest in a string of recent misfortune that the telescope suffered in recent years.
One of the auxiliary cables that helps support a metal platform in place above the observatory broke on August 10, triggering a 100-foot-long gash on the telescope’s reflector dish. The damage happened during the Tropical Storm Isaias, but it isn’t clear yet just how the damage occurred.
“We have a team of experts assessing the situation,” said Francisco Cordova, the director of the observatory, in a statement. “Our focus is assuring the safety of our staff, protecting the facilities and equipment, and restoring the facility to full operations as soon as possible.”
The break occurred early in the morning when the storm was kicking in, according to Cordova. When the three-inch cable fell it also damaged about six to eight panels in the Gregorian Dome and twisted the platform used to access the dome. The observatory is now closed pending an investigation.
The observatory is managed by the University of Central Florida and it began operating in 1963. Over the years, it has produced many scientific discoveries in the solar system and beyond, being considered one of the most powerful telescopes in the world at the time. It’s also where SETI, the search of extraterrestrial intelligence, began. Nowadays, Arecibo is used by scientists around the world to conduct research in the areas of atmospheric sciences, planetary sciences, radio astronomy and radar astronomy. It is also home to a team that runs the Planetary Radar Project supported by NASA’s Near-Earth Object Observations Program.
While the damage was shocking to everyone, it’s far from the first time that Arecibo had to deal with technical difficulties. Back in September 2017, Puerto Rico was severely hit by Hurricane Maria, which knocked power across the island for months. An antenna suspended over the observatory fell and punctured a dish. The hurricane came at a difficult time for the observatory. The National Science Foundation, which owns Arecibo, was already considering giving the observatory to someone else so it could focus on other projects. The foundation finally did an agreement with a group of three institutions to take over the operations.
Then, earthquakes hit the island in January of this year. The tremors were as strong as 6.4 magnitudes and it made it impossible to carry out observations, with no visitors allowed on-site. The dish wasn’t damaged but operations couldn’t be restarted until the tremors fully stopped.
There are many telescopes on Earth and in space, providing us with important information and carrying out different research projects. So why not set up one on the moon, with craters in lieu of a telescope dish?
The space agency gave a new round of grants for its favorite innovative space projects and one is a plan to fit a 1 kilometer (3,281 foot) radio telescope inside a crater on the far side of the Moon.
The moon telescope project is one of 23 concepts that received part of a $7 million investment. The Phase I award consists of $125,000 to fund a nine-month study of the idea. Other concepts include investigating solar sails, lunar landing pads, and a robotic explorer for Saturn’s moon Enceladus.
NASA pointed out that these projects will mostly require a decade or more of technology development, and that they are not official NASA missions. These fascinating ideas are worthy of deeper investigation, though, and could one day move from concept to reality.
The Lunar Crater Radio Telescope (LCRT) would be able to measure wavelengths and frequencies that can’t be detected from Earth, working unobstructed by the ionosphere or the various other bits of radio noise surrounding our planet.
“LCRT could enable tremendous scientific discoveries in the field of cosmology by observing the early universe in the 10–50m wavelength band (6–30MHz frequency band), which has not been explored by humans to date,” writes robotics technologist Saptarshi Bandyopadhyay, who pitched the proposal.
Bandyopadhyay’s proposal lists the benefits of locating a telescope on the far side of the moon, including that “the moon acts as a physical shield that isolates the lunar-surface telescope from radio interferences/noises from Earth-based sources, ionosphere, Earth-orbiting satellites, and sun’s radio-noise during the lunar night.”
According to the proposal, moon rovers would pull out a wire mesh some 1 kilometer across, inside a lunar crater than could be up to 5 kilometers (3.1 miles) in diameter. A suspended receiver in the center of the crater would complete the system.
Everything could be automated without any human operators, which would, in turn, mean a lighter and less expensive payload for the project to literally get off the ground. But this is still at the very early stage of planning, and it’s not clear yet exactly which crater would be used for the job.
“Building the largest filled-aperture radio telescope in the Solar System on the far side of the Moon is bound to create a lot of public excitement,” Bandyopadhyay and his colleagues write in a 2018 paper on the idea. “This concept would unlock the potential for ground-breaking scientific discoveries in radio astronomy.”
Out beyond the orbit of Neptune and the solar system’s seven other major planets lies a ring of icy bodies known as the Kuiper Belt. The disc that is 20 times as wide and an estimated 200 times as dense as the asteroid belt houses a wide array of objects, including its most famous inhabitant — the dwarf planet Pluto. But, it holds more than objects of ice and rock. The Kuiper Belt may hold the secrets of how the planets of the solar system formed, and the raw materials that created the worlds around us and our own planet.
“The Kuiper Belt is a repository of the solar system’s most primordial material and the long-sought nursery from which most short-period comets originate,” explains David C. Jewitt, an astronomer based at the University of California, Los Angeles, who is renowned for his study of the solar system and its smaller bodies. “The scientific impact of the Kuiper Belt has been huge, in many ways reshaping our ideas about the formation and evolution of the Solar System.”
Researchers now stand on the verge of unlocking these secrets with the investigation of the Kuiper Belt contact binary Arrokoth (previously known as ‘Ultima Thule’). On January 2019, the object — named for the Native American word for ‘sky’ — became the most distant object ever visited by a man-made spacecraft.
“Most of what we know about the belt was determined using ground-based telescopes. As a result, Kuiper Belt studies have been limited to objects larger than about 100 km because the smaller ones are too faint to easily detect,” says Jewitt. “Now, 5 years after its flyby of the 2000-km-diameter Kuiper Belt object Pluto, NASA’s New Horizons spacecraft has provided the first close-up look at a small, cold classical Kuiper Belt object.”
The data collected by the New Horizons probe has allowed three separate teams of researchers to conduct the most in-depth investigation of a Kuiper Belt object ever undertaken. In the process, they discovered that our current knowledge of how these objects form is very likely incorrect. From all the evidence the three teams collected, it seems as Kuiper Belts form as a result of a far more delicate, low-velocity process than previously believed. As most astrophysicists believe that these objects — planetesimals — acted as the seeds from which the planets grew, this new model changes our idea of how the solar system formed.
How Kuiper Belt Bodies Get in shape
The majority of the clues as to Arrokoth’s low-velocity formation originate from its unusual binary lobed shape. The larger lobe is joined to the smaller lobe by an extremely narrow ‘neck.’ What is especially interesting about this shape — reminiscent of a bowling pin or a snowman — is that the lobes are perfectly aligned.
John Spencer, Institute Scientist in the Department of Space Studies, Southwest Research Institute in Boulder, Colorado, led a team of researchers that reconstructed Arrokoth’s 3-dimensional shape from a series of high resolution black and white images. Spencer’s paper concludes that Arrokoth’s lobes are much flatter than was previously believed but despite this, both lobes are denser than expected.
William McKinnon, Professor of Earth and Planetary Sciences at the Califonia Institute of Technology, and his team ran simulations of different formation methods to see which conditions led to the shape recreated and Spencer and his colleagues.
McKinnon and his team discovered that the shape of Arrokoth could only be achieved as a result of a low-velocity formation–around 3 m/s. This presents a problem to current theories of how planetesimals form.
The suggested method of planetesimal formation suggests high-velocity particles smashing together in a process called hierarchical accretion. The simulations that McKinnon produced suggest that such high-velocity collisions would not have created a larger body, but rather, would have blown it apart. The geometrical alignment of the larger and smaller lobes indicates to the team that they were once co-orbiting bodies which gradually lost angular momentum and spiralled together, resulting in a merger.
“Arrokoth’s delicate structure is difficult to reconcile with alternative models in which Arrokoth Kuiper Belt objects are fragments of larger objects shattered by energetic collisions,” Jewitt says. This supports a method of planetesimal formation called ‘cloud collapse.’
“A variety of evidence from Arrokoth points to gravitational collapse as the formation mechanism. The evidence from the shape is probably most compelling,” William Grundy of Lowell Observatory says. “Gravitational collapse is a rapid but gentle process, that only draws material from a small region. Not the much more time consuming and violent process of hierarchical accretion – merging dust grains to make bigger ones, and so on up through pebbles, cobbles, boulders, incrementally larger and larger, with more and more violent collisions as the things crashing into each other.”
Grundy, whose team analysed the thermal emissions from Arrokoth’s ‘winter’ side, goes on to explain that the speed at which cloud collapse occurs and the fact that all the material that feeds it is local to it means that all the Kuiper planetesimals should be fairly uniform.
Cold Classicals: Untouched and unpolluted
Arrokoth is part of a Kuiper Belt population referred to as ‘cold classicals,’ this particular family of bodies is important to astrophysicists researching the origins of the solar systems. This is because, at their distance from the Sun within the Kuiper Belt, they have remained virtually untouched by both other objects and by the violent radiation of the Sun.
As many of these objects, Arrokoth in particular, date back 4 billion years to the very origin of the solar system, they hold an uncontaminated record of the materials from which the solar system emerged and of the processes at play in its birth.
Arrokoth has a relatively smooth surface in comparison with other comets, moons and planets within the solar system. It does show the signs of a few impacts, with one very noticeable 7km wide impact crater located of the smaller lobe. This few craters dotted across Arrokoth’s surface do seem to point to a few small high-velocity impacts. The characteristics of Arrokoth’s cratering allowed the team in infer its age of around 4 billion years. This places its birth right around the time the planets had begun to form in the solar system.
“The smooth, relatively un-cratered surface shows that Arrokoth is relatively pristine, so evidence of its formation hasn’t been destroyed by subsequent collisions,” Spencer explains. “The number of craters nevertheless indicates that the surface is very old, likely dating back to the time of accretion.
“The almost perfect alignment of the two lobes, and the lack of obvious damage where they meet, indicate gentle coalescence of two objects that formed in orbit around each other, something most easily accomplished by local cloud collapse.”
As mentioned above, Will Grundy and his team were tasked with the analysis of thermal emissions in the radio band emitted by the side of Arrokoth facing away from the Sun.
“We looked at the thermal emission at radio wavelengths from Arrokoth’s winter night side. Arrokoth is very cold, but it does still emit thermal radiation,” Grundy says. “The signal we saw was brighter, corresponding to a warmer temperature than expected for the winter surface temperature. Our hypothesis is that we are seeing emission from below the surface, at depths where the warmth from last summer still lingers.”
Grundy’s team also looked at the colour imaging of Arrokoth with the aim of determining what it is composed of. “We looked at the variation of colour across the surface, finding it to be quite subtle,” he says. “There are variations in overall brightness, but the colour doesn’t change much from place to place, leading us to suspect that the brightness variations are more about regional differences in surface texture than compositional differences.”
The team determined that Arrokoth’s dark red colouration is likely to be a result of the presence of ‘messy’ molecular jumbles of organic materials that occur when radiation drives the construction of increasingly complex molecules–known as tholins.
“One open question is where Arrokoth’s tholins came from,” Grundy says. “Were they already present in the molecular cloud from which the Solar System formed? Did they form in the protoplanetary nebula before Arrokoth accreted? Or did they form after Arrokoth accreted, through radiation from the Sun itself?”
The researcher says that all three are possible, but he considers the uniformity of Arrokoth’s colouration to favour the first two possibilities over the third. The team also searched Arrokoth for more recognisable organic molecules, spotting methanol–albeit frozen solid–but, not finding any trace of water. Something which came as a surprise to Grundy. “It was surprising not to see a clear signature of water ice since that’s such a common material in the outer solar system. Typically, comets have around 1% methanol, relative to their water ice.”
The team believe that this disparity arises from the fact that Arrokoth accreted in a very distinct chemical environment at the extreme edge of the nebula which collapsed to create the solar system.
“If it was cold enough there for carbon monoxide (CO) and methane (CH4) to freeze as ice onto dust grains, that would enable chemical mechanisms that create methanol and potentially destroy water, too. But those mechanisms could only work where these gases are frozen solid,” Grundy says. “Arrokoth appears to be sampling a region of the nebula where such conditions held.
“We have not seen comets so rich in methanol, which probably means we have not seen comets that formed in this outermost part of the nebula. Most of them probably originally formed closer to the Sun (or else at a different time in nebular history when the chemical conditions were somewhat different).”
Looking to future Kuiper Belt investigations
Investigating Kuiper Belt objects is no walk in the park, with difficulties arising from both the disc’s distance from the Sun and from the fact that Kuiper Belt objects tend to be very small. Grundy explains that as sunlight falls off by the square of its distance, object s as far away as the Kuiper Belt require the most powerful telescopes to do much of anything.
“Sending a spacecraft for a close-up look is great to do, but it took New Horizons 13 years to reach Arrokoth,” Grundy says. “It’ll probably be some time yet before another such object gets visited up-close by a spacecraft.”
“For flybys, the journey times are very long–we flew for 13 years to get there–navigation is difficult because we don’t know the orbits of objects out there very well, we’d only been tracking Arrokoth for 4 years,” Spencer explains. “The round-trip light time is long, which makes controlling the spacecraft more challenging, and light levels are very low, so taking well-exposed, unblurred, images is difficult.”
Spencer adds that from Earth, objects like Arrokoth are mostly very faint, meaning only a small fraction of them have been discovered and learning about their detailed properties is difficult even with large telescopes. These difficulties mean that one of the things left to discover is just how common bi-lobed contact binaries like Arrokoth are in the Kuiper Belt. “Some evidence from lightcurves suggests up to 25% of cold classical could be contact binaries,” he says. ” We know that many of them are binaries composed of two objects orbiting each other, however.”
Fortunately, telescope technology promises to make leaps and bounds over the coming decades, with the launch of the space-based James Webb Space Telescope (JWST) in 2021 and the completion of the Atacama Desert based Extremely Large Telescope (ELT) in 2026.
“Both will help,” says Grundy. “Larger telescopes are needed to collect more light and feed it to more sensitive instruments. JWST and the new generation of extremely large telescopes set to come online over the coming years will enable new investigations of these objects.”
In terms of future spacecraft visits, Grundy believes that researchers and engineers should be thinking small, literally: “If technical advances were to enable highly miniaturized spacecraft to be flown to the Kuiper belt more quickly, that could enable a lot of things. The big obstacles to doing that with today’sCubeSats are power, longevity, and communications, but the rapid advance of technology makes me hopeful that it will be possible to do a whole lot more with tiny little spacecraft within a few decades.
“It’s funny how progress calls for ever bigger telescopes and ever smaller spacecraft.”
Of course one of the most lasting changes that result from this landmark triad of studies on Arrokoth published in Science is the move away from hierarchical formation models and the adoption of a gravitational or cloud collapse model to explain the creation of planetesimals. This shift will resolve one of the long-standing issues with the hierarchical model, the fact that they work quite well to grow things from dust size to pebble size, but once pebble size is reached, the particles quickly spiral-in toward the Sun.
“I think it will shift the focus to the circumstances that trigger the collapse. It’s a very fast way of making a planetesimal–decades instead of hundreds of millennia–but the circumstances have to be right for instabilities to concentrate solids enough for them to collapse,” Grundy explains. “It will be interesting to map out where and when planetesimals should form, what their size distributions should be, and where the solids that they are formed from should have originated.”
W. M. Grundy et al., Science
W. B. McKinnon et al.,
J. R. Spencer et al., Science 10.1126/science.aay3999 (2020).
D. C. Jewitt et al., Science 10.1126/science.aba6889 (2020).
In what could be a key step to solve several long-standing mysteries around it, a group of astronomers have released the highest resolution image of the sun, obtained thanks to observations by the Inouye solar telescope in Hawaii.
The images show a never-before-seen level of structure hidden within the plasma exterior. This was achieved thanks to the telescope’s 30km resolution, which is more than twice that of the next best solar observatories around the world. The telescope is located at a 3,000 meters volcano on the island of Maui.
“These are the highest resolution images of the solar surface ever taken,” said Thomas Rimmele, the director of the Inouye solar telescope project. “What we previously thought looked like a bright point – one structure – is now breaking down into many smaller structures.”
The solar telescope revealed the sun’s surface to be speckled with granular structures, each the size of France. At the center of each grain, there are rising columns of plasma, heated to almost 6,000ºC (10,800F). When the plasma cools, it goes back below the surface through channels between the granular structures.
Valentin Pillet, the director of the National Solar Observatory, described the challenges that involved taking the solar images. Keeping the telescope’s mirror at ambient temperature while looking at the sun proved difficult, as temperature deviation causes air turbulences that can alter the images.
At the same time, Pillet said that in order to carry out the project they emptied a swimming pool worth of ice into eight tanks every day. Then, during the day, coolant was routed through the ice tanks and distributed through the pipes of the observatory. They also positioned 100 air jets behind the main mirror.
The experts at the observatory also deflected the incoming sunlight from the primary mirror into a chamber of mirrors, located below the dome. The light was then bounced from mirror to mirror. The observatory is equipped with a full set of instruments, which will allow measuring the magnetic field from the surface of the sun later in the year.
Such observations will help to solve long-standing mysteries around the sun, such as why its atmosphere is heated to millions of degrees when the surface is 6,000ºC. Understanding the physics behind the solar flares will be able to improve the ability to predict space weather.
“On Earth, we can predict if it is going to rain pretty much anywhere in the world very accurately, and space weather just isn’t there yet,” said Matt Mountain, president of the Association of Universities for Research in Astronomy. “What we need is to grasp the underlying physics behind space weather, and this starts at the Sun, which is what the Inouye Solar Telescope will study over the next decades.”
After an initial setback yesterday (17/12/19) due to a software error, the European Space Agency’s (ESA) CHaracterising ExOPlanets Satellite — or CHEOPS — telescope has finally launched from the European Spaceport in Kourou, French Guiana.
CHEOPS was aboard a Russian Soyuz-Fregat rocket which blasted off at 9:54 am European time. The Rocket will take approximately 145 minutes to place the CHEOPS unit into a rare pole to pole low-Earth orbit.
The telescope hitched a ride with an Italian radar satellite, the rocket’s primary payload.
CHEOPS is the result of a collaboration between 11 member countries within the ESA, with Switzerland taking the lead on the project. Two of the country’s leading Universities — the University of Geneva and the University Bern — worked together to equip CHEOPS with a state of the art photometer.
This powerful device will measure changes in the light emitted by nearby stars as planets pass by — or transit — them. This examination reveals many details about a planet’s characteristics, its diameter, and details of its atmosphere in particular.
By combining a precise measurement of diameter with a measurement of mass, collected by an alternative method, researchers will then be able to determine a planet’s density. This, in turn, can lead to them deducing its composition and internal structure.
CHEOPS was completed in a short time with an extremely limited budget of around 50-million Euros.
“CHEOPS is the first S-class mission for ESA, meaning it has a small budget and a short timeline to completion,” explains Kate Issak, an ESA/CHEOPS project researcher. “Because of this, it is necessary for CHEOPS to build on existing technology.”
CHEOPS: Informed by the past, informing the future
The project is acting as a kind of ‘middle-man’ between existing exoplanet knowledge and future investigations. It is directed to perform follow-up investigations on 400–500 ‘targets’ found by NASA planet-hunter Transiting Exoplanet Survey Satellite (Tess) and its predecessor, the Kepler observatory. Said targets will occupy a size-range of approximately Earth-Neptune.
This mission then fits in with the launch of the James Webb Telescope in 2021 and further investigation methods such as the Extremely Large Telescope array in the Chilean desert, set to begin operations in 2026. It will do this by narrowing down its initial targets to a smaller set of ‘golden targets’. Thus, meaning its investigation should help researchers pinpoint exactly what planets in close proximity to Earth are worthy of follow-up investigation.
“It’s very classic in astronomy that you use a small telescope ‘to identify’, and then a bigger telescope ‘to understand’ — and that’s exactly the kind of process we plan to do,” explains Didier Queloz, who acted as chair of the Cheops science team. “Cheops will now pre-select the very best of the best candidates to apply to extraordinary equipment like very big telescopes on the ground and JWST. This is the chain we will operate.”
Queloz certainly has pedigree when it comes to exoplanets. The astrophysics professor was jointly awarded the 2019 Nobel Prize in Physics for the discovery of the first exoplanet orbiting a Sun-like star with Michel Mayor.
The first task of the science team operating the satellite, based out of the University of Bern, will be to open the protective doors over the 30 cm aperture telescope — thus, allowing CHEOPS to take its first glimpse of the universe.
A team of researchers from Carnegie just discovered 20 new moons orbiting around Saturn, raising the total count to 82 — barely surpassing Jupiter’s 79.
Depending on when you finished school, you might have learned that Jupiter or Saturn has the most moons. Kids finishing school this year will probably learn that Saturn has the most moons, as 20 new moons measuring around 5 km (3 miles) in diameter have been discovered around Saturn.
Three of these moons orbit Saturn “normally”, rotating in the same direction the planet does. The rest of 17, however, have a so-called retrograde rotation, meaning they rotate in the opposite direction.
“It’s exciting to find them,” said Scott Sheppard, an astronomer who led the work at the Carnegie Institution for Science in Washington DC. “These moons are very far away from the planet.” Each is about three miles across.
However, it’s not just a quirky new find or something topic students will have to learn — learning more about these moons could teach us something new about the evolution of their host planets, and the solar system as a whole.
“Studying the orbits of these moons can reveal their origins, as well as information about the conditions surrounding Saturn at the time of its formation,” said Dr Scott Sheppard, from the Carnegie Institution for Science in Washington DC, who led the team that discovered the moons.
Nowadays, if an asteroid zooms by a planet, the planet wouldn’t be able to capture it, because there’s nothing to slow it down and dissipate its energy. But in the solar system’s infancy, things were quite different.
In the early days of the solar system, when Saturn was still just forming, a cloud of dust and gas surrounded the planet. During those days, if an asteroid flew by Saturn, the cloud dissipated the asteroid’s energy, allowing the planet to capture the asteroid.
These moons have been alongside Saturn for a long time, it just took astronomers a long time to find them because they are so small.
These moons are at the very edge of what current satellites can discover — particularly, researchers used the Subaru telescope on Hawaii’s Mauna Kea volcano for their detection. From 2004 to 2007, Sheppard and colleagues used Subaru to sweep Saturn’s area looking for undiscovered moons. They did find some intriguing points of light, but it took a while to prove that they were in fact moons.
That’s why this discovery was more than a decade in the making. From 2004 to 2007, Sheppard and his colleagues used Subaru to comb the area around Saturn to search for undiscovered moons. While they did see some intriguing points of light, they struggled to prove that those pinpricks were, in fact, orbiting Saturn. It was improved computer algorithms that allowed astronomers to make the confirmation.
“We thought they were moons of Saturn, but we weren’t able to get full orbits to determine this,” said Dr Sheppard. “By using this new computer power, I was able to link these 20 objects that we thought were moons to officially find orbits for them.”
None of the new moons have names yet. Sheppard and colleagues have invited the public to offer suggestions for a period of 2 months, until December 6th.
Even without names, Saturn is, at least temporarily, the king of moons — overthrowing Jupiter from that position. However, that might not last for long. New, more powerful telescopes are currently being built, and there is a good chance that they will be able to discover even moons that are currently undetectable. Our current best capabilities allow astronomers to detect moons around 3 miles across around Saturn, and 1 mile across around Jupiter.
Engineers at the NASA have put together the two halves of the Webb telescope.
The team has successfully put together the Webb telescope proper (the part of the craft which includes the mirrors and science instruments) with the rest of the spacecraft and its sunshield. The next step is to connect and test all the electronics on the different parts.
James Webb, assembled
“The assembly of the telescope and its scientific instruments, sunshield and the spacecraft into one observatory represents an incredible achievement by the entire Webb team,” said Bill Ochs, Webb project manager at the NASA Goddard Space Flight Center in Greenbelt, Maryland.
The James Webb telescope is the product of 20 years’ work from thousands of individuals across NASA, the European Space Agency, the Canadian Space Agency, Northrop Grumman, and other industrial and academic bodies.
Yesterday, the team used a crane to slowly and gently guide the telescope into place while ensuring that all points of contact were properly aligned and seated.
Next, they’re going to fully-deploy the craft’s intricate, five-layer sunshield. This sunshield is designed to keep Webb’s mirrors and scientific instruments cold by blocking infrared light from the Earth, moon, or sun.
All of the craft’s main components have been tested individually through all of the environments they would encounter during the mission: a rocket ride and orbiting mission a million miles away from Earth. Now that Webb is a fully assembled observatory, it will go through additional environmental and deployment testing to ensure mission success.
Since the mission hinges on the heat shield being able to deploy — and deploy in the correct shape — NASA wants to test its functionality on the assembled craft as quickly as possible.
“This is an exciting time to now see all Webb’s parts finally joined together into a single observatory for the very first time,” said Gregory Robinson, the Webb program director at NASA Headquarters in Washington, D.C.
“The engineering team has accomplished a huge step forward and soon we will be able to see incredible new views of our amazing universe.”
The James Webb spacecraft is scheduled to launch in 2021, when it will become the world’s most powerful space science observatory.
Our understanding of the universe may need some reconsidering, a new study suggests.
These galaxies are selected from a Hubble Space Telescope program to measure the expansion rate of the universe, called the Hubble constant. The value is calculated by comparing the galaxies’ distances to their apparent rate of recession away from Earth (due to the relativistic effects of expanding space). Credit: NASA, ESA, W. Freedman (University of Chicago), ESO, and the Digitized Sky Survey.
When Edwin Hubble announced that he discovered galaxies outside of our Milky Way, the announcement caused quite a stir — but this was just the beginning. Hubble found that galaxies which were farther away moved away faster from us. It wasn’t just galaxies either: anywhere he looked, he found the same thing: the farther things are, the faster they move apart from each other. This was undeniable evidence that not only was the universe expanding, but the expansion was accelerating.
The unit of measurement for this universal expansion is called the Hubble Constant.
The Hubble Constant is one of the most important numbers in modern physics because it describes a fundamental feature of our universe. But this rate of expansion is not easy to calculate. Most commonly, it is obtained by measuring the distance to distant galaxies and then calculating the redshift from these galaxies — in other words, by looking at how the wavelengths of light incoming from the galaxies are stretched. However, the different assumptions made in this calculation can strongly affect the result.
For the past century, astronomers have diligently measured the Hubble constant. In the 1990s, a team led by Wendy Freedman of the University of Chicago greatly refined the Hubble constant value to a precision of 10% — which was, fittingly, possible thanks to the Hubble telescope.
In more recent times, astronomers sought even higher precision. But the more they looked, the more they started to find discrepancies.
“Naturally, questions arise as to whether the discrepancy is coming from some aspect that astronomers don’t yet understand about the stars we’re measuring, or whether our cosmological model of the Universe is still incomplete,” University of Chicago astronomer Wendy Freedman said in a NASA press release.
“Or maybe both need to be improved upon.”
Recent studies have proposed somewhat different values for this universal expansion. Freedman’s most recent study, which has been accepted for publication in The Astrophysical Journal, sought to reconcile these values and serve as a tie-breaker — but instead, it added yet another value to be dealt with. According to what has been released so far, Freedman’s results indicate that the universe is expanding faster than most previous estimates. Their new observations, also made using Hubble, indicate that the expansion rate for the universe is just under 70 kilometers per second per megaparsec (km/sec/Mpc). One parsec is equivalent to 3.26 light-years distance, and a megaparsec is one million parsecs. This is one of the highest values for the universal expansion rate, but not the fastest — that one belongs to a team led by Adam Riess of the Johns Hopkins University and Space Telescope Science Institute, which found an expansion rate of 74 km/sec/Mp.
The differences are not trivial. Many modern cosmological concepts and calculations are based on the Hubble constant.
“The Hubble constant is the cosmological parameter that sets the absolute scale, size and age of the universe; it is one of the most direct ways we have of quantifying how the universe evolves,” said Freedman. “The discrepancy that we saw before has not gone away, but this new evidence suggests that the jury is still out on whether there is an immediate and compelling reason to believe that there is something fundamentally flawed in our current model of the universe.”
NASA’s upcoming mission, the Wide Field Infrared Survey Telescope (WFIRST), is expected to enable astronomers to calculate the Hubble constant even more accurately, also enabling researchers to calculate how this expansion rate changed through cosmic time. Needless to say, the mission, scheduled to launch in the mid-2020s, is eagerly awaited by the astronomic community.
In 2015, the world got understandably excited as SpaceX mastermind Elon Musk announced the launch of a new satellite fleet that would give the world faster and cheaper internet. But as the first few satellites were launched, it made a lot of astronomers unhappy.
The constellation, which so far consists of 60 satellites but is set to be expanded to 12,000, add more clutter and significantly reduce our view of the cosmos, potentially dealing an important blow to many, many space surveys.
Screenshot taken from a video shot by Marco Langbroek with a group of SpaceX Starlink satellites passing over the Netherlands on May 24, 2019.
When the first satellites were launched, the event was tracked all around the world. Astronomer Marco Langbroek noted on his blog a calculation of where the satellites would be orbiting. He set up his camera and patiently waited, but not for long: he quickly observed a string of bright dots flying across the sky. The satellites were so bright that they were even visible to the naked eye in certain instances prompting some people to UFO sightings.
Sure enough, their brightness has diminished partly as they stabilized into orbit, but for astronomers, this was a clear message: observations are bound to get more difficult, and there’s going to be a lot more objects in the way.
To get a sense of the current situation, there are currently 2,100 active satellites orbiting our planet. If 12,000 are added by SpaceX alone, it would add an unprecedented level of visual clutter for astronomers — and SpaceX is just one of the companies who want to put internet satellites into orbit.
“People were making extrapolations that if many of the satellites in these new mega-constellations had that kind of steady brightness, then in 20 years or less, for a good part of the night anywhere in the world, the human eye would see more satellites than stars,” Bill Keel, an astronomer at the University of Alabama, told AFP.
Jonathan McDowell of the Harvard Smithsonian Center for Astrophysics also adds that at least during some parts of the year, things will get a bit more problematic for astronomers.
“So, it’ll certainly be dramatic in the night sky if you’re far away from the city and you have a nice, dark area; and it’ll definitely cause problems for some kinds of professional astronomical observation.”
SpaceX’s declared goal is a lofty one: to provide broadband internet connectivity to underserved areas of the planet and offer cheaper, more reliable service to all the world. The cashflow received from this venture would help the company advance its Mars flight plans, helping mankind achieve its space exploration dreams. Yet at the same time, this is placing a hurdle in the way of astronomers.
If there’s anything we can learn from this story, is that things are most often complex, and even with good intentions, planetary-scale projects can have important side-effects which need to be accounted for.
Ever had a moment when you feel like you’re important and what you do matters? Here’s the antidote.
Infrared view of a section within the North Galactic Pole, a region near the constellation Coma Berenices. Every point of light in this image represents an entire galaxy. Image: ESA/Herschel/SPIRE; M. W. L. Smith et al 2017.
At a first glance, not much is going on in this image — just some yellowish noise on a blue-green background. But this photo from ESA’s Herschel Space Observatory shows much more than you’d think: every yellowish speck is a galaxy.
This is the North Galactic Pole, an area which covers some 180 square degrees of the sky and features a galaxy-rich cluster known as the Coma Cluster, which contains at least 1,000 points of light (read: galaxies).
[panel style=”panel-default” title=”Spherical coordinates” footer=””]Just like on Earth, astronomers define observations using a coordinate system — but unlike the XYZ coordinate systems you might be more familiar with, they use a spherical coordinate system. In the former, a point is described by its X, Y, and Z coordinates.
A visual depiction of the spherical coordinate system for a point P. The polar angle is in blue, the azimuthal angle in red.
In a spherical system, a point is also described by three coordinates but, in this case, it’s the radial distance of that point from a fixed origin, the polar angle, and the azimuth angle. It can be a bit weird to wrap your head around, but it can be much easier to navigate astronomical observations. [/panel]
So here, we have the North Galactic Pole, which lies far from the cluttered disc of the Milky Way and offers a good view of the distant Universe beyond our home galaxy.
Zoomed-in view showing about 8 percent of the entire photo width. How many galaxies can you count? Image: ESA/Herschel/SPIRE; M. W. L. Smith et al 2017. via Gizmodo.
The image above was taken at a wavelength of 250 μm, in the infrared range (the human visible range is generally within 0.4 – 0.7 μm). It was taken using the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS). Unfortunately, Herschel isn’t active anymore — it functioned from 2009 to 2013, using its instruments to study the sky in the far infrared range.
Aside from making us feel incredibly small and showing us just how puny our struggles really are, these pictures also help astronomers to estimate how many galaxies there are in the Universe. Recent surveys have estimated that number to be around 20 trillion, which is 20 times more than previous estimates gathered using the Hubble telescope. All these galaxies are packed with billions of stars, which can also host planets just like Earth.
Similar to how stars are formed, the most popular theory among today’s scientists regarding the creation of planets is that they are a result of a nebula breaking down. During the long evolution of the deteriorating gaseous cloud, the nebula transforms into a structure called a protoplanetary disk, with a newly-formed star at its center. Such a disk provides a place of incubation for developing planets.
Just recently, for the first time on record, young planets-to-be (also referred to as protoplanets) developing in one of these protoplanetary disks were actually “weighed”. Several scientific papers published earlier this month as inclusions in the Astrophysical Journal Letters discuss a new mode of operation which can be employed to calculate various physical attributes of these protoplanets. It’s also rather accurate and dependable.
One group of astronomers headed by Richard Teague was responsible for the discovery of two young planets having a mass close to the size of the mass of Jupiter, the largest planet in our solar system. The two bodies orbit a star which has been labeled HD 163296. This four-million-year-old ball of burning gas is still a youngster as a star the size of our Sun would have a normal life expectancy of about 10 billion years and beyond.
A Developing Star System. Source: SciTechDaily.
But a separate party of scientists, this one based in Australia and headed by Christophe Pinte, was also spending time examining the same system. They noticed a third protoplanet in a revolution around the very same star. However, the finding attributed to Pinte’s team was a young planet nearly twice as massive as the gas giant Jupiter.
Both of the teams employed data from the Atacama Large Millimeter/submillimeter Array (ALMA). This is a system of radio telescopes located in Chile, South America. The two teams of astronomers closely examined the motion of the nebulous gas. Both managed to develop a process of measuring the gas’s velocity by observing the change in the wavelength of light emitted by carbon monoxide molecules.
The gravitational pull of a planet would best explain the gaseous movements. Richard Teague thinks this method of measurement could be used effectively in observing many other stars and protoplanets. In this way, he hopes scientists will be able to discover what types of protoplanets are most common in the cosmos.
NASA’s future planet hunter has arrived — and it’s set for glory.
Like Kepler, TESS will be using the transit method illustrated here. Essentially, as a planet passes in front of its star, it creates a dip in the star’s luminosity, which can be detected. This is called a transit. Image credits: NASA Goddard Space Flight Center.
The Kepler telescope ushered in a new age of space exploration, enabling astronomers to discover thousands of exoplanets. It was a magnificent tool that was successful beyond our wildest dreams. However, it’s nearing the end of its lifetime. Crippled and almost out of fuel, Kepler is fast approaching its conclusion. But rest assured — NASA already has its replacement prepared.
NASA’s Transiting Exoplanet Survey Satellite, or TESS, will be carried in outer space by SpaceX’s Falcon 9 rocket in just a few days, on April 16, where it’s set for even greater success than Kepler. Think of it this way: if Kepler was looking through a straw, TESS will be visualizing 90% of the night sky. In other words, Kepler had a very narrow surveying angle, whereas TESS will have a much broader angle — overall, the area covered by TESS will be about 350 times larger than what Kepler could witness. This is largely owed to its unusual orbit — TESS has a never-before-used orbit which was designed to minimize the time the telescope spends obstructed by Earth or the Moon. However, there’s a trade-off.
TESS will observe the southern skies first, and then the north. The survey strips will overlap near the celestial poles, creating pockets of sky that will have longer observation times. Conveniently, the patches of sky that will be observed the most by TESS are also in ideal viewing locations for the future James Webb Space Telescope, which will be able to study planets that TESS finds in more detail. Image credits: NASA / MIT.
TESS traded resolution for this larger angle — whereas Kepler was able to find planets up to 3,000 light years away, most of the exoplanets TESS finds will be just 30 to 300 light years away. Kepler has already discovered over 2,500 planets, with another 2,500 planet candidates being currently under review. TESS is expected to find 3,000 to 4,000 planets orbiting M-dwarves — relatively small and cold stars, red dwarfs of the M spectral type. Red dwarfs are by far the most common type of star in the Milky Way, but because of their low luminosity, they are difficult to study.
Currently, TESS is at Kennedy Space Center’s Payload Hazardous Servicing Facility, getting its thrusters fueled up for flight — and we couldn’t be more excited for this mission.