Astronomers have underestimated just how bright the low-frequency radio sky is, new measurements show.

The post Radio Astronomers Measure a Brighter Sky Than They Expected appeared first on Sky & Telescope.

Researchers have identified the most distant dormant black hole known, dating back to the universe’s early history. Astronomers have long relied on brilliant quasars, supermassive black holes actively feeding on surrounding matter, to study the early universe. Yet these luminous objects reveal only part of the story. Now, researchers have detected the most distant dormant [...]

A new cosmic bounce model suggests that remnants from a pre-Big Bang Universe may still exist today. What if some of the Universe’s oldest objects are actually older than the Big Bang itself? A new study from the University of Portsmouth suggests that ancient black holes may have survived from a time before the Universe [...]

A new study suggests that the collapse of a massive star could spark the creation of a tiny expanding universe rather than a black hole. The resulting object, called a gravastar, would avoid the singularity and event horizon that make black holes so puzzling. Massive stars produce light and heat through nuclear fusion in their [...]

A major challenge to dark energy, the mysterious force believed to be driving the universe’s accelerating expansion, has been overturned by a new study. Astronomers say a new analysis has reinforced one of the most important discoveries in modern cosmology, finding that the universe is still expanding at an accelerating rate. The result counters a [...]

On the evening of September 9, 1999, a Harvard graduate student named David Charbonneau drove to a parking lot in Boulder, Colorado, and let himself into a small wooden shed.

Inside was a telescope. Not a large one. The kind of instrument that, by professional astronomical standards, was almost embarrassingly small — a four-inch aperture, the size of something a serious amateur stargazer might keep in their backyard.

Charbonneau was twenty-five years old. He was working with the astronomer Tim Brown at the High Altitude Observatory, on what most of the established astronomical community considered, at best, a long shot. He was trying to detect a planet around another star — not by the wobble it caused in its star’s motion, the standard method of the time, but by the tiny shadow it would cast as it passed between Earth and the star’s face.

The expected dip was around 1%. Smaller than a passing insect crossing a porch light. From a wooden shed. Through Earth’s hazy atmosphere. With a telescope you could buy at a hobby shop.

What happened over the next few hours would help change the entire science of finding planets.

The star and the long shot

The target was HD 209458, a sun-like star about 150 light-years away in the constellation Pegasus.

Earlier that same year, two teams of astronomers using the Doppler radial-velocity method had detected a planet orbiting HD 209458. The radial-velocity method works by measuring the tiny gravitational wobble a planet causes in its host star — but it can’t directly prove the orbiting body is a planet. It only proves something is tugging on the star. To confirm the body was definitely a planet, and to measure its actual size and density, you needed a different kind of observation.

The geometry of HD 209458’s orbit happened to be favourable. If the planet’s orbital plane was aligned correctly with our line of sight, it would pass directly in front of its star — and from Earth, that would look like a brief, faint dimming of the starlight. A transit. The technique had been theorised for decades but never used to detect a planet.

Tim Brown’s small Colorado setup, called STARE — Stellar Astrophysics and Research on Exoplanets — was built precisely for this kind of measurement. The four-inch telescope, mounted in a small wooden shed in the parking lot of the High Altitude Observatory, would stare at fields of stars and watch for the tiny dimming events that might reveal a planet crossing.

Charbonneau later recalled the moment Brown introduced him to the equipment. “Tim pointed me to a small wooden shed in a parking lot,” he said. The setup was modest enough that the obvious question was whether such a small instrument could possibly detect something that subtle.

What he saw

The answer arrived on September 9, 1999.

As Charbonneau and Brown watched, HD 209458’s brightness dipped — by close to 2% — for about three hours, then returned to normal. A week later, on September 16, it dipped again. Both events matched the predicted orbital period of the planet that the radial-velocity teams had already proposed. It was the unmistakable signature of a planet — eventually named HD 209458b — passing in front of its star.

It was the first time any human being had directly watched the shadow of a planet outside our solar system cross its star.

Charbonneau and Brown were not alone in the moment. A separate team led by Gregory Henry, working independently, detected a partial transit of the same star in November of that year. Their two papers were submitted to The Astrophysical Journal within a day of each other, and published simultaneously in the same issue. The detection of HD 209458b became one of the cleanest examples of competitive science producing duplicate, mutually confirming results.

Why the small telescope worked

It is easy to assume that finding something as faint as a planetary shadow requires the largest, most sophisticated instruments. The HD 209458 detection demonstrated that this is not true.

What made the transit detectable wasn’t the size of the telescope. It was the precision and stability of the measurement. STARE was designed to do one specific thing exceptionally well: measure the brightness of stars with high consistency over time. A tiny dip — even a 1% dip — becomes detectable if your noise floor is low enough.

This was the deeper lesson buried in Charbonneau’s observation. The transit method didn’t require enormous apertures. It required steady measurements of brightness, repeated over long periods. That insight changed how the entire field thought about exoplanet detection — and shaped what came next.

Thousands of worlds

The transit method, validated by that September observation, became the most successful exoplanet detection technique in history.

A decade after Charbonneau’s observation, NASA launched the Kepler space telescope — a mission built on exactly the principle the Colorado shed had demonstrated. Kepler stared continuously at about 150,000 stars in the constellation Cygnus, watching for the tiny dips in light that a transiting planet would cause. By the end of its mission in 2018, Kepler had confirmed more than 2,600 exoplanets, with thousands of additional candidates still being analysed.

The total number of confirmed exoplanets now stands at over 6,000, with the NASA Exoplanet Archive recording 6,298 confirmed worlds as of June 2026. The transit method has contributed the majority of those detections.

Two newer space telescopes — TESS and the upcoming Nancy Grace Roman Space Telescope — are extending the same basic technique. Roman, scheduled to launch in late 2026, is expected to identify and characterise as many as 100,000 additional exoplanets over its five-year primary mission.

All of it, traceable back to a small wooden shed in a Boulder parking lot, on a September night when a 25-year-old graduate student looked at a tiny dip in a star’s light and recognised what he was seeing.

That dip is now one of the most photographed light curves in modern astronomy. The shed is still there.

The post On a September night in 1999, a 25-year-old graduate student stepped into a modest wooden shed in a Colorado parking lot and used a tiny four-inch telescope to spot a 1% dip in a star’s light—a backyard experiment that proved alien planets could be tracked by their shadows and opened the floodgates to discovering thousands of worlds appeared first on Space Daily.

AI could accelerate the hunt for new physics, but sometimes it knows too much to see what’s right in front of it. Artificial intelligence could make it much cheaper and faster to search for new laws of physics, according to a new study published in the Journal of Cosmology and Astroparticle Physics (JCAP). But the [...]

A new detector-based method clarifies how gravitational waves should be measured in an evolving universe. Imagine trying to measure a ripple on the surface of a pond while the pond itself is slowly changing shape. That is the challenge scientists face when they study gravitational waves not as isolated signals from colliding black holes, but [...]

Does the fact that we see light from very distant galaxies prove that the one-way speed of light is finite? Dr. Jason Lisle responds to this question. The conventionality thesis plays a critical role in understanding the issue, suggesting that measurements usually assume an isotropic light speed.

A new mathematical breakthrough sheds light on how tiny black holes could emerge from critical states of spacetime. Black holes are often portrayed as cosmic giants, swallowing stars and shaping entire galaxies. But some of the most intriguing black holes predicted by physics could be far smaller than an atom. For decades, scientists have known [...]

My book, "The Physics of Creation: The Creator’s Ultimate Design for Earth," is now available for download at CreationToday.org for under $5. The book offers a unique perspective on the universe, linking physical laws to an intelligent Creator, and explores how scientific principles align with the biblical creation narrative.

There is a pattern found in nature. It is indeed the largest pattern there is. It is so vast that it spans the universe, filling up its observable volume. The pattern is made of individual units in the same way your body is made of cells — if each of your cells were a galaxyContinue reading "Untangling the cosmic web"

The post Untangling the cosmic web appeared first on Astronomy Magazine.

New mathematical research suggests dark energy may not be needed to explain the accelerating expansion of the universe, challenging the foundations of the standard cosmological model. Mathematicians are questioning whether dark energy is actually responsible for the universe’s accelerating expansion. In a new study published in Proceedings of the Royal Society A, researchers at the [...]

Recent findings from the James Webb Space Telescope (JWST) indicate that Little Red Dots (LRD) could be primordial black holes, challenging the big bang theory. The data suggests these objects formed too soon for typical galaxy evolution, raising questions about cosmological interpretations and the nature of observational evidence.

In early 1987, a team led by MIT’s Jacqueline Hewitt was imaging radio-emitting objects with the Very Large Array radio telescope as part of a gravitational lens survey. The unusual appearance of object MG1131+0456 – an oval with elongated bright spots at the ends – led to further investigation, and the researchers eventually concluded itContinue reading "June 9, 1988: First image of an Einstein ring"

The post June 9, 1988: First image of an Einstein ring appeared first on Astronomy Magazine.

Small galaxies are expected to have even smaller companion galaxies, according to current cosmological models. A recent study takes a look at one dwarf galaxy and finds more tiny companions than anticipated. 

Cosmology Predicts Satellite Galaxies

Critical to our understanding of dark matter and galaxy formation, satellite galaxies are small, faint galaxies surrounding a larger host galaxy. The leading cosmological model, known as lambda cold dark matter (ΛCDM), predicts dark matter halos of all masses to host smaller dark matter subhalos whose luminous counterparts make up satellite galaxies. 

While the satellite systems of Milky Way-like galaxies are well characterized, the companions of dwarf galaxies are less well studied. Despite being significantly smaller, dwarf galaxies should also host even smaller satellites galaxies around them. These satellites push the limits of observations — extremely faint and hard to distinguish from background sources, dwarf galaxy satellites require innovative imaging techniques to discover. 

In recent years, new surveys have identified a number of satellites around dwarf galaxies that appear broadly consistent with ΛCDM predictions, though the sample size is still small. Continuing the search for little galaxies’ little galaxies is critical to testing the ΛCDM framework and will further our understanding of galaxy formation on the smallest scales. 

Searching for Satellites Around DDO 161

Diving into a specific system, a team led by Jiaxuan Li (李嘉轩) from Princeton University began an in-depth search for satellites around the dwarf galaxy DDO 161. Prior to this study, DDO 161 was known to have one companion, UGCA 319, that is about 10 times smaller than its host. 

The authors used data from the Legacy Surveys to search for satellites within about 400,000 light-years of DDO 161 — the expected reach of DDO 161’s gravitational influence. After removing bright sources and smoothing the image to bring out very faint objects, they found eight satellite galaxy candidates including UGCA 319.

To confirm if these candidates were actual satellites of DDO 161, the team performed follow-up observations of the seven unconfirmed sources with the Magellan 6.2-meter telescope. Using the surface brightness fluctuation technique — measuring how a galaxy’s light fluctuates from pixel to pixel to determine its distance — the authors confirmed that three of the candidates are located at a similar distance to DDO 161 and are likely satellites. With the previously confirmed companion UGCA 319, DDO 161 has four satellite galaxies with stellar masses above 250,000 solar masses, making it the most satellite-rich dwarf galaxy known to date. 

Too Many Satellites

How does DDO 161 compare to theoretical predictions for galaxies of its size? The authors ran cosmological simulations to quantify the expected satellite populations around galaxies of similar size to DDO 161. Just as it is an outlier observationally, DDO 161 is also an outlier when compared to the simulation results that predicted fewer satellite galaxies in similarly massive host systems. 

Making sure to cover all bases, the authors considered their observational uncertainties, limitations of the simulations, different relationships between stellar and dark matter halo mass, and possible environmental effects. None of these checks could, at this point, sufficiently explain the satellite overabundance in DDO 161, introducing a possible “too-many-satellites” problem for this galaxy. A larger sample of satellites around dwarf galaxies is necessary to better understand this discrepancy, test our current cosmological framework, and give new insight into galaxy formation on small scales. 

Citation

“A Possible ‘Too-many-satellites’ Problem in the Isolated Dwarf Galaxy DDO 161,” Jiaxuan Li et al 2026 ApJL 998 L24. doi:10.3847/2041-8213/ae3ddd

The post Satellite Surplus Around Dwarf Galaxy DDO 161 appeared first on AAS Nova.

Editor’s Note: Astrobites is a graduate-student-run organization that digests astrophysical literature for undergraduate students. As part of the partnership between the AAS and astrobites, we occasionally repost astrobites content here at AAS Nova. We hope you enjoy this post from astrobites; the original can be viewed at astrobites.org.

Title: Examining the Nature of the Starless Dark Matter Halo Candidate Cloud-9 with Very Large Array Observations
Authors: Alejandro Benítez-Llambay et al.
First Author’s Institution: University of Milano-Bicocca
Status: Published in ApJ

Astronomy, in many ways, is the study of light — in every wavelength that exists — coming at us from light-years away. But most of the mass in our universe is made of dark matter, a material that neither emits nor reflects any light. So, how exactly are we supposed to find this dark matter? Well, the dominant theory of what our universe is made of, Lambda cold dark matter (ΛCDM), predicts that this dark matter can form small halos — regions of gravitationally bound matter — that host reservoirs of cold gas but no stars. While we cannot directly observe dark matter, this cold gas can reflect light at radio wavelengths. Finding these dark halos, referred to as reionization-limited neutral atomic hydrogen clouds (RELHICs), is therefore rather important to confirm ΛCDM. The authors of this article are attempting to do just that by taking a close look at Cloud-9, a potential RELHIC.

How to “See” in the Dark

Cloud-9 was first discovered in 2023 when a team of astronomers noticed an excess of neutral hydrogen (HI) gas with no bright stars around it, near the spiral galaxy Messier 94 (M94). This discovery was made with the Five-hundred-meter Aperture Spherical radio Telescope (FAST), which doesn’t have the best resolution. For reference, this article found Cloud-9’s diameter to be roughly 3 arcminutes in the sky, while FAST’s resolution is 2.9 arcminutes. So, the authors of this article decided to look at Cloud-9 again, this time with the Very Large Array (VLA), an array of radio telescopes that can pick out more of the structure of this system.

With this upgraded resolution, the authors were able to get a clearer picture of the shape of Cloud-9 and compare it to the previous study (see Figure 1). They found that Cloud-9 was slightly smaller and much more lopsided than previously thought. This funky shape is likely due to gravitational interactions with the larger nearby galaxy M94, causing the gas in Cloud-9 to squish and stretch.

RELHIC or Just RELHIC-tively Dim?

To determine if Cloud-9 really is a RELHIC, the authors needed to compare its HI radial density profile to the profiles of simulated RELHICs. Density profiles are a good tool to use here since although we don’t fully understand what dark matter is, we do know how it will affect things around it gravitationally. If the only matter hosted by Cloud-9 is HI gas and dark matter, then that gas will have a specific distribution that we can observe. If other baryonic matter is hosted by Cloud-9 that we just aren’t picking up right now, it will affect that density profile.

The authors found that for a detailed, general simulation the profiles did not match well, specifically in the outer regions. But when they compared it to a sphere of gas with a constant, specific temperature, they were able to get the fits to line up (see Figure 2). However, the authors point out that these simulations are isolated, meaning there is no big galaxy next to them affecting their shape, unlike Cloud-9.

The authors also tried to test another explanation for Cloud-9’s apparent lack of stars: the stars are there but just too dim for us to see right now. The Milky Way sits near many ultra-faint dwarf galaxies, which are small and have quite dim stellar populations. We’ve only just developed telescopes in the last few years that can take in enough light to see these galaxies, and we might not be able to detect stars in an ultra-faint dwarf galaxy as far away from us as Cloud-9. The authors compare the HI density profile of Cloud-9 to that of Leo T, a nearby ultra-faint dwarf galaxy. They find that these profiles match up better than for the general RELHIC simulations, particularly in the innermost regions of Cloud-9 and Leo T.

What Are the Next Steps?

The authors conclude that, as of right now, they can’t definitively say whether Cloud-9 is or is not a RELHIC, but there are a few things astronomers can do to clear things up. First, theorists can re-run the RELHIC simulations with halos that have been affected by gravity like Cloud-9. This will allow them to better compare their observations to the simulations.

Second, observers can image Cloud-9 with an optical telescope that is powerful enough to detect any stars that could be there. They suggest the Hubble Space Telescope since it would be able to detect the brightest handful of stars in the potential dim population. JWST would be an even better choice, with its even deeper imaging capabilities, but it is very difficult to get observing time on it. (JWST recently received the most proposals in one year for any telescope ever!)

We will likely have to wait a bit for a definitive answer on the nature of Cloud-9, but either way the authors are excited by this gas cloud. Either it is the first starless dark matter halo, a confirmation of one of the predictions of ΛCDM, or it is the most distant ultra-faint dwarf galaxy ever detected! Although Cloud-9 is not much to look at right now, you should still definitely keep your eye on it.

Original astrobite edited by Maggie Verrico and Cole Meldorf.

About the author, Veronika Dornan:

Veronika is a final-year PhD candidate at McMaster University. Her research is in observations of extragalactic globular star clusters and what they can tell us about galaxy evolution and dark matter distribution in the universe.

The post A Long, Hard Look at (Potentially) Nothing to See appeared first on AAS Nova.

Understanding the nature of our cosmos requires an accurate map of how galaxies are spread throughout it. For decades, astronomers suspected that something vast lurked behind the Milky Way’s dense, dusty disk in our sky. There were indirect, subtle distortions present in galaxy motions that we could see, showing unexplained gravitational pulls. But the structureContinue reading "Giant supercluster discovered hiding behind the Milky Way"

The post Giant supercluster discovered hiding behind the Milky Way appeared first on Astronomy Magazine.

Scientists say that they’ve just detected a massive cloud of gas some 3 billion lightyears in diameter, floating in space roughly 7 billion light years away from us. This is pretty cool, but the problem is that our current models of the universe say that it (and other massive structures like it) just shouldn’t exist. Let’s take a look.