All posts tagged: Astronomy

For the first time, astronomers identify the edge of the Milky Way’s disc

For the first time, astronomers identify the edge of the Milky Way’s disc

Published by Jenni Sidey

The Milky Way does not come with a clean outer line. Its disc does not stop the way a coastline does. It fades, becoming harder and harder to define as stars grow sparse and the structure stretches into the dark. That uncertainty has made one question especially stubborn for astronomers: where does the galaxy’s star-forming disc actually end? A new analysis points to an answer. By tracing the ages of stars across the Milky Way, an international team of astronomers found that most of the galaxy’s star formation is confined to a region within about 40,000 light-years of the Galactic Centre. Past that point, the pattern of stellar ages shifts in a way that suggests the main star-forming disc has already run out. According to Dr. Karl Fiteni from the University of Insubria, “The extent of the Milky Way’s star-forming disc has long been an open question in Galactic archaeology. By mapping how stellar ages change across the disc, we now have a clear, quantitative answer.” Inside the star-forming disc abundant cold gas fuels star …

Cosmic simulations reveal how galaxies formed and evolved over billions of years

Cosmic simulations reveal how galaxies formed and evolved over billions of years

Published by Jenni Sidey

Cold gas does not look dramatic at first glance. Neither does dust. Yet those two quiet ingredients sit at the center of a new effort to build a far more realistic picture of how galaxies formed. They help explain how galaxies changed and spread across the universe over billions of years. A new suite of simulations called COLIBRE now tracks both, along with the violent push and pull from stars and black holes, in a way earlier large-scale models usually could not. The result is a set of virtual universes that, according to the research team, reproduces real galaxies with striking accuracy, from the nearby universe to the distant young cosmos seen by the James Webb Space Telescope. That matters because galaxy simulations have become one of astronomy’s main testing grounds. They let scientists check whether the standard cosmological model can actually produce the kinds of galaxies telescopes observe. In this case, the answer looks stronger than before. Essential components “Much of the gas inside real galaxies is cold and dusty, but most previous large …

How to Watch the 2026 Lyrids Meteor Shower at Its Peak

How to Watch the 2026 Lyrids Meteor Shower at Its Peak

Published by skeptic

In mid-April, astronomy enthusiasts will be able to enjoy one of the classic celestial spectacles. The meteor shower known as the Lyrids will illuminate the sky, especially in the northern hemisphere, and anyone will be able to see it with the naked eye, weather permitting—if they know where to look. The Lyrids began to appear as early as April 14, but their activity peaks between the night of April 21 and the early morning of April 22, according to NASA. During those hours, the shower will show 15 to 20 meteors per hour under dark skies. The shower gets its name because the meteors appear to emerge from the constellation Lyra. Locating the radiant is simple if you use an astronomical mapping app: Just find Vega, the fifth brightest star in the sky, surpassed only by Sirius, Canopus, Alpha Centauri A, and Arcturus. Once you locate it, look around it; the luminous traces of the Lyrids will seem to be projected from that point due to a perspective effect. Keep in mind that it takes …

Mississippi State physicist creates neutron star reaction in the lab

Mississippi State physicist creates neutron star reaction in the lab

Published by Jenni Sidey

For years, physicists have wondered whether one unstable form of copper might act like a traffic jam inside some of the most violent explosions in the universe. That question matters because those explosions, called Type-I X-ray bursts, are part of the cosmic machinery that helps build heavier elements. Hydrogen and helium dominated the early universe. Much of what came later, including the oxygen in the air and the iron deep inside Earth, had to be forged in stars and stellar blasts. Now, a team led by Mississippi State physicist Jaspreet Randhawa has directly measured a key nuclear reaction tied to that process. The result suggests the suspected slowdown is much weaker than scientists feared. Therefore, heavier elements have a clearer path to form during explosive bursts on neutron stars. “The universe began almost entirely with hydrogen and helium,” Randhawa said. “Every heavier element, from the oxygen we breathe to the iron in Earth’s core, was forged later in stars and stellar explosions. By identifying how stellar explosions build heavier elements, scientists gain a clearer picture …

Dense dark matter clumps link three strange objects across the universe

Dense dark matter clumps link three strange objects across the universe

Published by Jenni Sidey

A tiny object half a universe away, a scar in a stream of stars circling the Milky Way, and an unusual star cluster in a nearby satellite galaxy may not seem related at first glance. Yet a new study argues they could all trace back to the same kind of invisible structure. This structure is built from a more active version of dark matter than physicists usually assume. That idea matters because dark matter is not a side note in cosmic history. It makes up about 85% of the universe’s matter. However, no one has seen it directly. Scientists infer its presence from gravity, from the way galaxies rotate, how galaxy clusters behave, and how light bends on its way to Earth. For years, the standard picture has treated dark matter as cold and collisionless. In that view, its particles drift through one another without much fuss. The model works well on large scales. But some smaller, denser structures have kept standing out as awkward exceptions. A team led by UC Riverside physicist Hai-Bo Yu …

Undergraduate students built a cavity detector to search for axion dark matter

Undergraduate students built a cavity detector to search for axion dark matter

Published by Jenni Sidey

Dark matter is supposed to be everywhere, threaded through the Milky Way and outnumbering ordinary matter by a wide margin. Yet after decades of effort, nobody has caught it directly. That gap between certainty and absence has helped turn modern cosmology into a field of giant machines, giant budgets and giant collaborations. So there is something striking about a recent axion search that went in the opposite direction. A team of then-undergraduate students at the University of Hamburg built a compact cavity detector. They ran it inside a powerful magnet and used it to probe one narrow slice of the dark matter problem. They did not find a signal. However, what they did find was a way to rule out axions with certain properties in that range. This tightened the map for future searches and showed that careful, smaller-scale physics can still leave a mark on one of science’s biggest mysteries. The work, now published in the Journal of Cosmology and Astroparticle Physics, focused on axions, hypothetical particles long considered one of the strongest candidates …

How Can Astronauts Tell How Fast They’re Going?

How Can Astronauts Tell How Fast They’re Going?

Published by skeptic

Let’s use our car again, but this time we’ll get real numbers from the accelerometer in our smartphone. Say we start at a red light and then accelerate at 2 m/s2 (meters per second squared) for five seconds. From the equation above, Δv1 would be 2 x 5 = 10 m/s, so that’s our velocity. Now, after cruising for a while, we accelerate again at 1 m/s2 for five more seconds. Δv2 is then 1 x 5 = 5 m/s. Adding these two changes, our velocity is now 15 m/s. And so on. The only problem is that inertial measurement isn’t as accurate as the Doppler method over long periods, because small errors will keep accumulating. That means you need to recalibrate your system periodically using some other method. Optical Navigation On Earth, people have long navigated by the stars. In the northern hemisphere, just find Polaris. It’s called the North Star because Earth’s axis of rotation points right at it. That’s why it appears stationary, while the other stars seem to revolve around it. …

Astronomers discover three distinct groups of merging black holes

Astronomers discover three distinct groups of merging black holes

Published by Jenni Sidey

Black hole collisions do not appear to come from one simple cosmic recipe. After studying more than 150 mergers detected through gravitational waves, astronomers say the growing catalog points instead to three distinct groups of merging black holes. Each group seems to carry its own signature in mass, spin, and how often the mergers happened across cosmic time. Taken together, the pattern suggests that these violent collisions are being built in more than one kind of environment. Their analysis focuses on the fourth gravitational-wave transient catalog from the LIGO-Virgo-KAGRA Collaboration, known as GWTC-4. That catalog includes more than 150 detected black hole mergers, enough for researchers to stop treating these events as a single blended population and start asking whether different families are hiding inside the data. Artist’s impression of a pair of black holes merging, involving one with unusual spin. (CREDIT: Carl Knox, OzGrav, Swinburne University of Technology) Not one family, but three One clue came from the masses. When the researchers looked across the full sample, they did not see a smooth spread. …

DESI completes largest-ever map of the Universe

DESI completes largest-ever map of the Universe

Published by skeptic

The Dark Energy Spectroscopic Instrument (DESI) has reached a defining milestone in modern cosmology, completing its original five-year survey and delivering the most detailed map of the Universe ever constructed. Operating from the Kitt Peak National Observatory in Arizona, DESI has charted more than 47 million galaxies and quasars in three dimensions. The result is a high-resolution cosmic map that stretches across billions of years, offering scientists an unprecedented dataset to probe how the Universe has evolved. Originally scheduled to run through a five-year mission, the project exceeded expectations both in speed and scale. Its success has now secured an extension through 2028, with plans to expand and refine this already vast map of the Universe. How DESI mapped the cosmos On April 15, DESI quietly marked the completion of its primary survey. Its 5,000 fibre-optic “eyes” scanned a region near the Little Dipper, repeatedly locking onto distant sources of light. Each observation captured photons that had travelled for billions of years before reaching Earth. At the heart of DESI is a highly coordinated system. …

Astronomers find compelling new evidence of the first stars formed after the Big Bang

Astronomers find compelling new evidence of the first stars formed after the Big Bang

Published by Jenni Sidey

A faint glow of helium, hanging near one of the earliest known galaxies, may be the clearest sign yet that astronomers have finally caught the universe’s first stars in action. The signal comes from a tiny object nicknamed Hebe, sitting about 3 kiloparsecs from GN-z11, a galaxy seen as it existed roughly 400 million years after the Big Bang. Using the James Webb Space Telescope, researchers say they have now confirmed a strange helium emission first noticed earlier, and the case has only grown stronger. No metal lines turned up in the data. That absence matters. The earliest stars, often called Population III stars, are thought to have formed from almost pure hydrogen and helium, before the universe had been enriched with heavier elements such as carbon, oxygen, and iron. For years, they have remained a missing piece in astronomy, predicted by theory but frustratingly hard to pin down with observations. That is why this small patch of light has drawn so much attention. Continuum-subtracted map of the HeII emission at the redshift of Hebe …