Amazing Science

Thanks to data from a magnified, multiply imaged supernova, a team led by University of Minnesota Twin Cities researchers has successfully used a first-of-its-kind technique to measure the expansion rate of the Universe. Their data provide insight into a longstanding debate in the field and could help scientists more accurately determine the Universe's age and better understand the cosmos. The work is divided into two papers, respectively published in Science, one of the world's top peer-reviewed academic journals, and The Astrophysical Journal, a peer-reviewed scientific journal of astrophysics and astronomy.

In astronomy, there are two precise measurements of the expansion of the Universe, also called the "Hubble constant." One is calculated from nearby observations of supernovae, and the second uses the "cosmic microwave background," or radiation that began to stream freely through the Universe shortly after the Big Bang. However, these two measurements differ by about 10 percent, which has caused widespread debate among physicists and astronomers. If both measurements are accurate, that means scientists' current theory about the make-up of the universe is incomplete.

"If new, independent measurements confirm this disagreement between the two measurements of the Hubble constant, it would become a chink in the armor of our understanding of the cosmos," said Patrick Kelly, lead author of both papers and an assistant professor in the University of Minnesota School of Physics and Astronomy. "The big question is if there is a possible issue with one or both of the measurements. Our research addresses that by using an independent, completely different way to measure the expansion rate of the Universe."

The University of Minnesota-led team was able to calculate this value using data from a supernova discovered by Kelly in 2014 -- the first ever example of a multiply imaged supernova, meaning that the telescope captured four different images of the same cosmic event. After the discovery, teams around the world predicted that the supernova would reappear at a new position in 2015, and the University of Minnesota team detected this additional image.

These multiple images appeared because the supernova was gravitationally lensed by a galaxy cluster, a phenomenon in which mass from the cluster bends and magnifies light. By using the time delays between the appearances of the 2014 and 2015 images, the researchers were able to measure the Hubble Constant using a theory developed in 1964 by Norwegian astronomer Sjur Refsdal that had previously been impossible to put into practice.

The researchers' findings don't absolutely settle the debate, Kelly said, but they do provide more insight into the problem and bring physicists closer to obtaining the most accurate measurement of the Universe's age. "Our measurement favors the value from the cosmic microwave background, although it is not in strong disagreement with the supernova value," Kelly said. "If observations of future supernovae that are also gravitationally lensed by clusters yield a similar result, then it would identify an issue with the current supernova value, or with our understanding of galaxy-cluster dark matter."

Using the same data, the researchers found that some current models of galaxy-cluster dark matter were able to explain their observations of the supernovae. This allowed them to determine the most accurate models for the locations of dark matter in the galaxy cluster, a question that has long plagued astronomers.

A "beautiful effect" predicted by quantum electrodynamics (QED) can explain the puzzling first observations of polarized X-rays emitted by a magnetar -- a neutron star featuring a powerful magnetic field, according to a Cornell astrophysicist. The extremely dense and hot remnant of a massive star, boasting a magnetic field 100 trillion times stronger than Earth's, was expected to generate highly polarized X-rays, meaning that the radiation's electromagnetic field did not vibrate randomly but had a preferred direction.

But scientists were surprised when NASA's Imaging X-ray Polarimetry Explorer (IXPE) satellite last year detected that lower- and higher-energy X-rays were polarized differently, with electromagnetic fields oriented at right angles to each other.

NASA’s James Webb Space Telescope has begun to shed light on formative years in the history of the universe that have thus far been beyond reach: the formation and assembly of galaxies. For the first time, a protocluster of seven galaxies has been confirmed at a distance that astronomers refer to as redshift 7.9, or a mere 650 million years after the big bang. Based on the data collected, astronomers calculated the nascent cluster’s future development, finding that it will likely grow in size and mass to resemble the Coma Cluster, a monster of the modern universe.

“This is a very special, unique site of accelerated galaxy evolution, and Webb gave us the unprecedented ability to measure the velocities of these seven galaxies and confidently confirm that they are bound together in a protocluster,” said Takahiro Morishita of IPAC-California Institute of Technology, the lead author of the study published in the Astrophysical Journal Letters. The precise measurements captured by Webb’s Near-Infrared Spectrograph (NIRSpec) were key to confirming the galaxies’ collective distance and the high velocities at which they are moving within a halo of dark matter – more than two million miles per hour (about one thousand kilometers per second).

The spectral data allowed astronomers to model and map the future development of the gathering group, all the way to our time in the modern universe. The prediction that the protocluster will eventually resemble the Coma Cluster means that it could eventually be among the densest known galaxy collections, with thousands of members. “We can see these distant galaxies like small drops of water in different rivers, and we can see that eventually they will all become part of one big, mighty river,” said Benedetta Vulcani of the National Institute of Astrophysics in Italy, another member of the research team.

Galaxy clusters are the greatest concentrations of mass in the known universe, which can dramatically warp the fabric of spacetime itself. This warping, called gravitational lensing, can have a magnifying effect for objects beyond the cluster, allowing astronomers to look through the cluster like a giant magnifying glass. The research team was able to utilize this effect, looking through Pandora’s Cluster to view the protocluster; even Webb’s powerful instruments need an assist from nature to see so far.

Exploring how large clusters like Pandora and Coma first came together has been difficult, due to the expansion of the universe stretching light beyond visible wavelengths into the infrared, where astronomers lacked high-resolution data before Webb. Webb’s infrared instruments were developed specifically to fill in these gaps at the beginning of the universe’s story.

The seven galaxies confirmed by Webb were first established as candidates for observation using data from the Hubble Space Telescope’s Frontier Fields program. The program dedicated Hubble time to observations using gravitational lensing, to observe very distant galaxies in detail. However, because Hubble cannot detect light beyond near-infrared, there is only so much detail it can see. Webb picked up the investigation, focusing on the galaxies scouted by Hubble and gathering detailed spectroscopic data in addition to imagery.

The research team anticipates that future collaboration between Webb and NASA’s Nancy Grace Roman Space Telescope, a high-resolution, wide-field survey mission, will yield even more results on early galaxy clusters. With 200 times Hubble's infrared field of view in a single shot, Roman will be able to identify more protocluster galaxy candidates, which Webb can follow up to confirm with its spectroscopic instruments. The Roman mission is currently targeted for launch by May 2027.

These objects are more than 100 times brighter than they should be. Observations by the agency’s NuSTAR X-ray telescope support a possible solution to this puzzle.

Exotic cosmic objects known as ultra-luminous X-ray sources produce about 10 million times more energy than the Sun. They’re so radiant, in fact, that they appear to surpass a physical boundary called the Eddington limit, which puts a cap on how bright an object can be based on its mass. Ultra-luminous X-ray sources (ULXs, for short) regularly exceed this limit by 100 to 500 times, leaving scientists puzzled.

In a recent study published in The Astrophysical Journal, researchers report a first-of-its-kind measurement of a ULX taken with NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR). The finding confirms that these light emitters are indeed as bright as they seem and that they break the Eddington limit. A hypothesis suggests this limit-breaking brightness is due to the ULX’s strong magnetic fields. But scientists can test this idea only through observations: Up to billions of times more powerful than the strongest magnets ever made on Earth, ULX magnetic fields can’t be reproduced in a lab.

Breaking the Limit

Particles of light, called photons, exert a small push on objects they encounter. If a cosmic object like a ULX emits enough light per square foot, the outward push of photons can overwhelm the inward pull of the object’s gravity. When this happens, an object has reached the Eddington limit, and the light from the object will theoretically push away any gas or other material falling toward it.

That switch – when light overwhelms gravity – is significant, because material falling onto a ULX is the source of its brightness. This is something scientists frequently observe in black holes: When their strong gravity pulls in stray gas and dust, those materials can heat up and radiate light. Scientists used to think ULXs must be black holes surrounded by bright coffers of gas. But in 2014, NuSTAR data revealed that a ULX by the name of M82 X-2 is actually a less-massive object called a neutron star. Like black holes, neutron stars form when a star dies and collapses, packing more than the mass of our Sun into an area not much bigger than a mid-size city.

This incredible density also creates a gravitational pull at the neutron star’s surface about 100 trillion times stronger than the gravitational pull on Earth’s surface. Gas and other material dragged in by that gravity accelerate to millions of miles per hour, releasing tremendous energy when they hit the neutron star’s surface. (A marshmallow dropped on the surface of a neutron star would hit it with the energy of a thousand hydrogen bombs.) This produces the high-energy X-ray light NuSTAR detects.

The recent study targeted the same ULX at the heart of the 2014 discovery and found that, like a cosmic parasite, M82 X-2 is stealing about 9 billion trillion tons of material per year from a neighboring star, or about 1 1/2 times the mass of Earth. Knowing the amount of material hitting the neutron star’s surface, scientists can estimate how bright the ULX should be, and their calculations match independent measurements of its brightness. The work confirmed M82 X-2 exceeds the Eddington limit.

On October 9, 2022, an intense pulse of gamma-ray radiation swept through our solar system, overwhelming gamma-ray detectors on numerous orbiting satellites, and sending astronomers on a chase to study the event using the most powerful telescopes in the world. The new source, dubbed GRB 221009A for its discovery date, turned out to be the brightest gamma-ray burst (GRB) ever recorded.

In a new study that appears today in Astrophysical Journal Letters, observations of GRB 221009A spanning from radio waves to gamma-rays, including critical millimeter-wave observations with the Center for Astrophysics | Harvard & Smithsonian's Submillimeter Array (SMA) in Hawaii, shed new light on the decades-long quest to understand the origin of these extreme cosmic explosions. This study is part of a series of discoveries that are to be published as a collection in Astrophysical Journal Letters.

The gamma-ray emission from GRB 221009A lasted over 300 seconds. Astronomers think that such "long-duration" GRBs are the birth cry of a black hole, formed as the core of a massive and rapidly spinning star collapses under its own weight. The newborn black hole launches powerful jets of plasma at near the speed of light, which pierce through the collapsing star and shine in gamma-rays.

With GRB 221009A being the brightest burst ever recorded, a real mystery lay in what would come after the initial burst of gamma-rays. "As the jets slam into gas surrounding the dying star, they produce a bright 'afterglow' of light across the entire spectrum," says Tanmoy Laskar, assistant professor of physics and astronomy at the University of Utah, and lead author of the study. "The afterglow fades quite rapidly, which means we have to be quick and nimble in capturing the light before it disappears, taking its secrets with it."

As part of a campaign to use the world's best radio and millimeter telescopes to study the afterglow of GRB 221009A, astronomers Edo Berger and Yvette Cendes of the Center for Astrophysics (CfA) rapidly gathered data with the SMA. "This burst, being so bright, provided a unique opportunity to explore the detailed behavior and evolution of an afterglow with unprecedented detail—we did not want to miss it," says Edo Berger, professor of astronomy at Harvard University and the CfA. "I have been studying these events for more than twenty years, and this one was as exciting as the first GRB I ever observed."

When the immense Arecibo radio telescope in Puerto Rico collapsed in 2020, it left gaping holes in astronomy. Now, a team from the California Institute of Technology (Caltech) hopes to address some of the gaps with a very different instrument: a tightly packed array of relatively inexpensive radio dishes that aims to quickly image radio sources across wide swaths of the sky. A nearly completed prototype array in California that the team calls a “radio camera” is already locating dozens of the distant, enigmatic eruptions called fast radio bursts (FRBs). Next year, the team hopes to begin construction on a much larger array with 2000 dishes that, together, will match the size of Arecibo.

Maura McLaughlin of West Virginia University is a leader of NANOGrav (the North American Nanohertz Observatory for Gravitational Waves), an effort to search for gravitational waves from supermassive black holes that relied on Arecibo for half its data. She says they took “a big sensitivity hit” when it was lost. “We really need a new telescope with a similar collecting area,” she says, and Caltech’s planned Deep Synoptic Array (DSA) fits that bill. “It will be a game changer.”

To gain sensitivity, radio astronomers can build big dishes like Arecibo or arrays of smaller dishes. But in most such arrays, the dishes are widely spaced, which sharpens their resolution but creates “a data deluge problem,” says Caltech’s Gregg Hallinan, DSA principal investigator (PI). Producing an image from a scattered array is like looking through a fragmented mirror, he says, and recreating the information from the missing parts is a complex nonlinear process known as deconvolution that can take weeks—or even years.

Many astronomers just want to regularly survey the sky for new objects or monitor sources for subtle changes without a heavy processing burden. Caltech’s solution, Hallinan says, is to “fill the mirror up” by packing low-cost dishes together. That makes deconvolution easier and should enable DSA to construct images in real time. The team has nearly finished assembling its prototype, the DSA-110, a T-shaped array of 95 dishes spaced 1 meter apart at Caltech’s Owens Valley Radio Observatory in California plus another 15 “outriggers” spread out more than a kilometer distant. To keep construction costs to $4 million, the instrument uses commercially available 4.6-meter dishes, homemade amplifiers, and wave-channeling feeds fashioned out of cake tins. Most radio telescopes require expensive cryogenic cooling to reduce amplifier noise, but Caltech’s engineers have squeezed similar performance out of room-temperature circuits. Co-PI Vikram Ravi admits they perform less well in the summer heat.

With a wide field of view, DSA-110 is good at detecting FRBs, intense blasts of radio waves lasting only milliseconds, coming from all over the sky. Several thousand have been detected, but little more than a dozen have been traced to their home galaxies, which might hold clues to what is powering the bursts. DSA-110 aims to localize many more. If a burst is detected, data from the outrigger dishes allow the telescope to zoom in and pin the FRB to its galaxy.

Black holes exist in our universe. That’s widely accepted today. Physicists have detected the X-rays emitted when black holes feed, analyzed the gravitational waves from black hole collisions and even imaged two of these behemoths. But mathematician Elena Giorgi of Columbia University studies black holes in a different way.

“Black holes are mathematical solutions to the Einstein equation,” Giorgi says — the “master equation” that is the basis of the general theory of relativity. She and other mathematicians seek to prove theorems about these solutions and otherwise probe the math of general relativity. Their goal: unlock unsuspected truths about black holes or verify existing suspicions.

Within general relativity, “one can understand clean mathematical statements and study those statements, and they can give an unambiguous answer within that theory,” says Christoph Kehle, a mathematician at ETH Zurich’s Institute for Theoretical Studies.

Mathematicians can solve equations that have bearing on questions about the nature of black holes’ formation, evolution and stability. Last year, in a paper posted online at arXiv.org, Giorgi and colleagues settled a long-standing mathematical question about black hole stability. A stable black hole, mathematically speaking, is one that if poked, nudged or otherwise disturbed will eventually settle back into being a black hole. Like a rubber band that has been stretched and then released, the black hole doesn’t rip apart, explode or cease to exist, but returns to something like its former self.

Black holes seem to be physically stable — otherwise they couldn’t endure in the universe — but proving it mathematically is a different beast. And a necessary feat, Giorgi says. If black holes are stable, as researchers presume, then the math describing them had better reflect that stability. If not, something is wrong with the underlying theory. “Most of my work,” Giorgi says, “is about proving things that we already expected to be true.”

Mathematics has a history of big contributions in the realm of black holes. In 1916, Karl Schwarzschild published a solution to Einstein’s equations for general relativity near a single spherical mass. The math showed a limit to how small a mass could be squeezed, an early sign of black holes. More recently, British mathematician Roger Penrose won the 2020 Nobel Prize in physics for his calculations showing that black holes were real-world predictions of general relativity. In a landmark paper published in 1965, Penrose described how matter could collapse to form a black hole with a singularity at its center.

New research led by Sascha Kempf of the Laboratory for Atmospheric and Space Physics (LASP) at CU Boulder finds that Saturn's rings are no more than 400 million years old. That's much younger than Saturn itself, which formed around 4.5 billion years ago.

Astronomers sorted through 200,000 Hubble images and made tens of thousands of measurements on them to look for any residual background glow in the sky, in an ambitious project called SKYSURF.

Aside from a tapestry of glittering stars, and the glow of the waxing and waning Moon, the nighttime sky looks inky black to the casual observer. But how dark is dark? To find out, astronomers decided to sort through 200,000 images from NASA's Hubble Space Telescope and made tens of thousands of measurements on these images to look for any residual background glow in the sky, in an ambitious project called SKYSURF. This would be any leftover light after subtracting the glow from planets, stars, galaxies, and from dust in the plane of our solar system (called zodiacal light).

When researchers completed this inventory, they found an exceedingly tiny excess of light, equivalent to the steady glow of 10 fireflies spread across the entire sky. That's like turning out all the lights in a shuttered room and still finding an eerie glow coming from the walls, ceiling, and floor.

The researchers say that one possible explanation for this residual glow is that our inner solar system contains a tenuous sphere of dust from comets that are falling into the solar system from all directions, and that the glow is sunlight reflecting off this dust. If real, this dust shell could be a new addition to the known architecture of the solar system.

This idea is bolstered by the fact that in 2021 another team of astronomers used data from NASA's New Horizons spacecraft to also measure the sky background. New Horizons flew by Pluto in 2015, and a small Kuiper belt object in 2018, and is now heading into interstellar space. The New Horizons measurements were done at a distance of 4 billion to 5 billion miles from the Sun. This is well outside the realm of the planets and asteroids where there is no contamination from interplanetary dust.

New Horizons detected something a bit fainter that is apparently from a more distant source than Hubble detected. The source of the background light seen by New Horizons also remains unexplained. There are numerous theories ranging from the decay of dark matter to a huge unseen population of remote galaxies.

"If our analysis is correct there's another dust component between us and the distance where New Horizons made measurements. That means this is some kind of extra light coming from inside our solar system," said Tim Carleton, of Arizona State University (ASU).

"Because our measurement of residual light is higher than New Horizons we think it is a local phenomenon that is not from far outside the solar system. It may be a new element to the contents of the solar system that has been hypothesized but not quantitatively measured until now," said Carleton.

The far side of the moon would benefit several types of astronomy. The most obvious one is radio astronomy, which can be conducted from the side of the Moon that always faces away from Earth – the so-called "far side".

The lunar far side is permanently shielded from the radio signals generated by humans on Earth. During the lunar night, it is also protected from the Sun. These characteristics makes it probably the most “radio-quiet” location in the whole solar system as no other planet or moon has a side that permanently faces away from the Earth. It is therefore ideally suited for radio astronomy.

Radio waves are a form of electromagnetic energy – as are, for example, infrared, ultraviolet and visible-light waves. They are defined by having different wavelengths in the electromagnetic spectrum. Radio waves with wavelengths longer than about 15m are blocked by Earth’s ionoshere. But radio waves at these wavelengths reach the Moon’s surface unimpeded. For astronomy, this is the last unexplored region of the electromagnetic spectrum, and it is best studied from the lunar far side.

Observations of the cosmos at these wavelengths come under the umbrella of “low frequency radio astronomy”. These wavelengths are uniquely able to probe the structure of the early universe, especially the cosmic “dark ages” – an era before the first galaxies formed. At that time, most of the matter in the universe, excluding the mysterious dark matter, was in the form of neutral hydrogen atoms. These emit and absorb radiation with a characteristic wavelength of 21cm. Radio astronomers have been using this property to study hydrogen clouds in our own galaxy – the Milky Way – since the 1950s.

Because the universe is constantly expanding, the 21cm signal generated by hydrogen in the early universe has been shifted to much longer wavelengths. As a result, hydrogen from the cosmic “dark ages” will appear to us with wavelengths greater than 10m. The lunar far side may be the only place where we can study this.

The astronomer Jack Burns provided a good summary of the relevant science background at the recent Royal Society meeting, calling far side of the moon a “pristine, quiet platform to conduct low radio frequency observations of the early Universe’s Dark Ages, as well as space weather and magnetospheres associated with habitable exoplanets”.

Signals from other stars As Burns says, another potential application of far side radio astronomy is trying to detect radio waves from charged particles trapped by magnetic fields – magnetospheres – of planets orbiting other stars. This would help to assess how capable these exoplanets are of hosting life. Radio waves from exoplanet magnetospheres would probably have wavelengths greater than 100m, so they would require a radio-quiet environment in space. Again, the far side of the Moon will be the best location.

A similar argument can be made for attempts to detect signals from intelligent aliens. And, by opening up an unexplored part of the radio spectrum, there is also the possibility of making serendipitous discoveries of new phenomena. We should get an indication of the potential of these observations when NASA’s LuSEE-Night mission lands on the lunar far side in 2025 or 2026.

Crater depths The Moon also offers opportunities for other types of astronomy as well. Astronomers have lots of experience with optical and infrared telescopes operating in free space, such as the Hubble telescope and JWST. However, the stability of the lunar surface may confer advantages for these types of instrument. Moreover, there are craters at the lunar poles that receive no sunlight. Telescopes that observe the universe at infrared wavelengths are very sensitive to heat and therefore have to operate at low temperatures. JWST, for example, needs a huge sunshield to protect it from the sun’s rays. On the Moon, a natural crater rim could provide this shielding for free.

The Moon’s relatively low gravity may also enable the construction of much larger telescopes than is feasible for free-flying satellites. These considerations have led the astronomer Jean-Pierre Maillard to suggest that the Moon may be the future of infrared astronomy. The cold, stable environment of permanently shadowed craters may also have advantages for the next generation of instruments to detect gravitational waves – “ripples” in space-time caused by processes such as exploding stars and colliding black holes.

Moreover, for billions of years the Moon has been bombarded by charged particles from the sun – solar wind – and galactic cosmic rays. The lunar surface may contain a rich record of these processes. Studying them could yield insights into the evolution of both the Sun and the Milky Way.

For all these reasons, astronomy stands to benefit from the current renaissance in lunar exploration. In particular, astronomy is likely to benefit from the infrastructure built up on the Moon as lunar exploration proceeds. This will include both transportation infrastructure – rockets, landers and other vehicles – to access the surface, as well as humans and robots on-site to construct and maintain astronomical instruments.

Most of the gamma ray sources in this animation are blazars, supermassive black holes with relativistic jets pointed at Earth.

We’ve come a long way since gamma rays were discovered. The late 1800s and early 1900s were a time of great scientific advancements. Scientists were just getting a handle on the different types of radiation. Radium featured prominently in the experiments, including one by French scientist Paul Ulrich Villard in 1900.

Radium decays readily, and scientists had already identified alpha and beta radiation coming from radium samples. But Villard was able to identify a third type of penetrating radiation so powerful even a layer of lead couldn’t stop it: gamma rays.

Now we have a gamma ray detector in space, and it’s showing us how the Universe sparkles with this powerful energy. Gamma rays are the most energetic form of light in the Universe, and as a new animation shows, the sky practically sparkles with flickering gamma-ray sources. The animation contains a year’s worth of observations from the Large Area Telescope (LAT) on NASA’s Fermi Gamma-ray Space Telescope. Each yellow circle is a gamma-ray source, and the expansion and contraction show how the source brightens and dims. The yellow circle is the Sun’s following its seemingly sinusoidal path relative to Earth.

The animation represents an entire year of observations. Each frame in the animation represents three days. The reddish-orange band that runs through the middle of the animation is the Milky Way’s central plane, which is a consistent gamma-ray producer.

Following in the footsteps of the Neptune image released in 2022, NASA’s James Webb Space Telescope has taken a stunning image of the solar system’s other ice giant, the planet Uranus. The new image features dramatic rings as well as bright features in the planet’s atmosphere.

When Voyager 2 looked at Uranus, its camera showed an almost featureless blue-green ball in visible wavelengths. With the infrared wavelengths and extra sensitivity of Webb we see more detail, showing how dynamic the atmosphere of Uranus really is.

On the right side of the planet there's an area of brightening at the pole facing the Sun, known as a polar cap. This polar cap is unique to Uranus -- it seems to appear when the pole enters direct sunlight in the summer and vanish in the fall; these Webb data will help scientists understand the currently mysterious mechanism.

Webb revealed a surprising aspect of the polar cap: a subtle enhanced brightening at the center of the cap. The sensitivity and longer wavelengths of Webb's NIRCam may be why we can see this enhanced Uranus polar feature when it has not been seen as clearly with other powerful telescopes like the Hubble Space Telescope and Keck Observatory.

At the edge of the polar cap lies a bright cloud as well as a few fainter extended features just beyond the cap's edge, and a second very bright cloud is seen at the planet's left limb. Such clouds are typical for Uranus in infrared wavelengths, and likely are connected to storm activity. This planet is characterized as an ice giant due to the chemical make-up of its interior. Most of its mass is thought to be a hot, dense fluid of "icy" materials -- water, methane, and ammonia -- above a small rocky core.

Uranus has 13 known rings and 11 of them are visible in this Webb image. Some of these rings are so bright with Webb that when they are close together, they appear to merge into a larger ring. Nine are classed as the main rings of the planet, and two are the fainter dusty rings (such as the diffuse zeta ring closest to the planet) that weren't discovered until the 1986 flyby by Voyager 2. Scientists expect that future Webb images of Uranus will reveal the two faint outer rings that were discovered with Hubble during the 2007 ring-plane crossing.

Webb also captured many of Uranus' 27 known moons (most of which are too small and faint to be seen here); the six brightest are identified in the wide-view image. This was only a short, 12-minute exposure image of Uranus with just two filters. It is just the tip of the iceberg of what Webb can do when observing this mysterious planet. In 2022, the National Academies of Sciences, Engineering, and Medicine identified Uranus science as a priority in its 2023-2033 Planetary Science and Astrobiology decadal survey. Additional studies of Uranus are happening now, and more are planned in Webb's first year of science operations.

The universe is expanding, with every galaxy beyond the Local Group speeding away from us. Today, most of the universe's galaxies are already receding faster than the speed of light. All galaxies currently beyond 18 billion light-years are forever unreachable by us, no matter how much time passes.

Our universe is full of stars and galaxies everywhere and in all directions. From our vantage point, we observe up to 46.1 billion light years away. Our visible universe contains an estimated ~ 2 trillion galaxies. However, most of them are already permanently unavailable for us.

Two of Uranus’ moons may be home to active oceans hidden beneath their surfaces. The new finding was uncovered when astronomers looked back at radiation data that Voyager 2 captured about the planet when it passed by over 40 years ago. According to that new data, the moons Ariel and Miranda could possibly house underground liquid water oceans. 

It’s an intriguing discovery that only helps to heighten the need for better exploration of Uranus and its 27 different moons. By getting a better understanding of the possible oceans on Uranus’ moons, we could possibly learn more about the moons themselves, where they originated from, and even whether or not they were ever capable of housing life of some significance. 

A new study on the findings has been accepted for publication in the journal Geophysical Research Letters. The study details the radiation readings that astronomers looked at, some of which seem to suggest that at least one of these two Uranus moons is ejecting material into space, possibly from an underground ocean.

The exact cause and means by which the plasma is being ejected into the solar system are unclear, as the readings we have to look at are all 40 years old at this point. However, with scientists calling for new missions to Uranus, we could likely see more data on the possibility that Uranus’ moons are harboring active oceans in the coming decades. 

Learning more about our solar system’s planets has always been a goal for astronomers. However, getting spacecraft to many of those planets isn’t always easy. That also doesn’t take into account the overall cost of such missions, either. The hope is that these suggestions that Uranus’ moons are hiding oceans could help spur the movement to create Uranus-focused exploration missions. 

Further, if NASA and other agencies show enough interest in exploring Uranus and the possibility of these moon-based oceans, then we could see more priority put on Uranus-focused exploration in the near future. 

New measurements by the James Webb Space Telescope found that a rocky exoplanet orbiting a star known as TRAPPIST-1 most likely has no atmosphere.  The finding squashes hopes that this intriguing world might host life. But don't despair — there are six more Earth-like exoplanets in the TRAPPIST-1 star system, and now that Webb has proven its ability to study them, we can hope for some more exciting news in the not so distant future.

Astronomers used the James Webb Space Telescope's Mid-Infrared Instrument (MIRI) to measure the temperature of the planet TRAPPIST-1b. Out of the seven planets that make up the TRAPPIST-1 star system, this planet orbits the closest to the parent star and is about 1.4 times as large as Earth.

The measurement, which according to the European Space Agency (ESA) represents Webb's first detection of "any form of light" emitted by a rocky exoplanet, revealed that the planet's daytime temperature was a scorching 446 degrees Fahrenheit (230 degrees Celsius). Astronomers think that's too high for the planet to have an atmosphere.

Thomas Greene, an astrophysicist in the Space Science and Astrobiology Division at NASA's Ames Research Center in California who led the observations, told Space.com in an email that he had hoped for a different result. "Some theory groups predicted that the planet would have a dense atmosphere, while others thought it might not," Greene said. "I was more disappointed than surprised to see it had no atmosphere."

The distance between TRAPPIST-1b and its star is only about one hundredth of the sun-Earth distance. That's 40 times closer than the distance between the sun and the solar system's innermost planet Mercury. Although the star at the center of the TRAPPIST-1 system is much dimmer than our sun, the planet still receives about four times as much starlight as Earth receives from the sun. Astronomers therefore didn't expect this planet to be habitable prior to ruling out the presence of an atmosphere. The observation, however, is still a breakthrough, as it shows that Webb can directly gather information about such distant Earth-like worlds. 

In the TRAPPIST-1 system, there are at least three planets — TRAPPIST-1e, 1f and 1g — that have conditions for the existence of liquid water on their surfaces and therefore might host life.  The TRAPPIST-1 system is a hugely popular target for exoplanet research and the best explored planetary system other than our own solar system, according to NASA. Located some 40 light-years away from the sun, the star at the center of the TRAPPIST-1 system is a so-called M dwarf. Sometimes also referred to as red dwarfs, these stars are the smallest known type of stars capable of burning hydrogen in their cores. They range in size from 0.08 to 0.6 times the size of the sun and are the most numerous type of star in our galaxy, the Milky Way.

"There are about ten times as many M stars like TRAPPIST-1 than G stars like the sun," Greene wrote. "M stars are also about twice as likely to have rocky, Earth-sized planets. Therefore about 95% of the Earth-sized rocky planets in the Milky Way will have stars like TRAPPIST-1 and not like the sun."