Astronomy

Why is there a spiral around the North Pole of Mars?

Face-on spiral galaxy NGC 6946 and open star cluster NGC 6939 share

If you know where to look, you can see a thermonuclear explosion from a white dwarf star.

Does the Milky Way always rise between these two rocks?

What do you see when you look into this sky?

It came from outer space.

The loss of snow cover in temperate forests is set to slow their growth and reduce their ability to remove carbon from the atmosphere, an overlooked consequence of climate change

The Milky Way and other similar galaxies have two distinct disk sections. One is the thin disk section, and it contains mostly younger stars with higher metallicity. The second is the thick disk, and it contains older stars with lower metallicity. The effort to study these disks in more galaxies and in greater detail has been stymied. But now we have the JWST, and researchers used it to examine more than 100 distant, edge-on galaxies.

Earth life is carbon-based, and without carbon, there would be no life. New research shows how Earth got its carbon from impactors, including a boost from Theia, the impactor that created the Moon. Jupiter also pitched in to help.

The search for dark matter requires all of the best models, theories, and ideas we can throw at it. A new paper from Julia Monika Koulen, Stefano Profumo, and Nolan Smyth from the University of California at Santa Cruz (UCSC) tackles the implications of the sizes and abundance of one of the more interesting dark matter candidates - primordial black holes (PBHs).

Proxima Centauri b is the closest known exoplanet that could be in the habitable zone of its star. Therefore, it has garnered a lot of attention, including several missions designed to visit it and send back information. Unfortunately, due to technological constraints and the gigantic distances involved, most of those missions only weigh a few grams and require massive solar scales or pushing lasers to get anywhere near their target. But why let modern technological levels limit your imagination when there are so many other options, if still theoretical, options to send a larger mission to our nearest potentially habitable neighbor? That was the thought behind the Master’s Thesis of Amelie Lutz at Virginia Tech - she looked at the possibility of using fusion propulsion systems to send a few hundred kilogram probe to the system, and potentially even orbit it.

What new methods can be developed in the search for extraterrestrial intelligence (SETI)? This is what a recent white paper submitted to the 2025 NASA Decadal Astrobiology Research and Exploration Strategy (DARES) Request for Information (RFI) hopes to address as a pair of researchers from the Breakthrough Listen project and Michigan State University discussed how high-energy astronomy could be used for identifying radio signals from an extraterrestrial technological civilization, also called technosignatures. This study has the potential to help SETI and other organizations develop novel techniques for finding intelligent life beyond Earth.

One of the most iconic cosmic scenes in the Universe lies nearly 3.8 billion light-years away from us in the direction of the constellation Carina. This is where two massive clusters of galaxies have collided. The resulting combined galaxies and other material is now called the Bullet Cluster, after one of the two members that interacted over several billion years. It's one of the hottest-known galaxy clusters, thanks to clouds of gas that were heated by shockwaves during the event. Astronomers have observed this scene with several different telescopes in multiple wavelengths of light, including X-ray and infrared. Those observations and others show that the dark matter makes up the majority of the cluster's mass. Its gravitational effect distorts light from more distant objects and makes it an ideal gravitational lens.

Earlier this year, asteroid 2024 YR4 was discovered and found to have a trajectory through the Earth/Moon system in 2032. The world's telescopes focused on the potential threat and downgraded the chance to negligible for the Earth...but it still has a non-zero chance of hitting the Moon. As the asteroid became too dim to continue observing, its Moon impact chance stood at 4%. When will we update this number? Not until it does another close flyby in 2028.

Astronomers have made a breakthrough by using 25 year old Hubble images to investigate a potential "rogue planet" drifting through space without a host star. When a brief gravitational microlensing event occurred in 2023, researchers discovered Hubble had photographed the same location in 1997, creating an unprecedented quarter century baseline. Finding no stellar companion in the archival data strengthened evidence for a rogue planet with mass between Earth and Saturn, demonstrating the scientific value of space telescope archives for studying these elusive worlds wandering the Galaxy alone.

Some of the most powerful supercomputers in the world are designed to simulate complex astrophysical processes, like what's happening inside a giant star as it's going supernova. But researchers have developed a new machine learning algorithm that was able to accurately simulate galaxy evolution with fewer computer resources and dramatically more quickly than a supercomputer, which could take years to fully process.

Astronomers once wondered if the Universe might one day collapse in on itself in a Big Crunch, but the discovery of dark energy suggested that the expansion of the Universe would accelerate, removing that possibility. New data from the Dark Energy Spectroscopic Instrument suggests that dark energy might be changing in strength over time, maybe even going negative. If that result holds, are we due for a Big Crunch? And how long would it take?

How do galaxies like ours continue producing stars long after they should have used up their star-forming gas. Somehow, an external gas source must find its way into the galaxy. New research has found evidence of gas clouds that found their way into a spiral galaxy, likely fueling continued star formation.