NASA’s Goddard Space Flight Center This simulated image shows how black holes bend a starry background and capture light. It’s that time again! Time for another model that will finally solve the mystery of dark matter. Or not, but it’s worth a shot. Until we directly detect dark matter particles, or until some model conclusively removes dark matter from our astrophysical toolkit the best we can do is continue looking for solutions. This new work takes a look at that old theoretical chestnut, primordial black holes, but it has a few interesting twists.1 Primordial black holes are hypothetical o ..read more

NASA, ESA, CSA, Leah Hustak (STScI) This artist concept portrays the brown dwarf W1935. Brown dwarfs span the line between planets and stars. By definition, a star must be massive enough for hydrogen fusion to occur within its core. This puts the minimum mass of a star around 80 Jupiters. Planets, even large gas giants like Jupiter, only produce heat through gravitational collapse or radioactive decay, which is true for worlds up to about 13 Jovian masses. Above that, deuterium can undergo fusion. Brown dwarfs lay between these two extremes. The smallest brown dwarfs resemble gas planets with ..read more

ESO/L. Calçada Artist’s impression of the magnetar in the star cluster Westerlund 1. One of the big mysteries about dark matter particles is whether they interact with each other. We still don’t know the exact nature of what dark matter is. Some models argue that dark matter only interacts gravitationally, but many more posit that dark matter particles can collide with each other, clump together, and even decay into particles we can see. If that’s the case, then objects with particularly strong gravitational fields such as black holes, neutron stars, and white dwarfs might capture and concentr ..read more

ESA Artist impression of glory on exoplanet WASP-76b. When light strikes the atmosphere all sorts of interesting things can happen. Water vapor can split sunlight into a rainbow arc of colors, corpuscular rays can stream through gaps in clouds like the light from heaven, and halos and sundogs can appear due to sunlight reflecting off ice crystals. And then there is the glory effect, which can create a colorful almost saint-like halo around objects. Like rainbows, glories are seen when facing away from the light source. They are often confused with circular rainbows because of their similarity ..read more

Ernest Wright/NASA’s Scientific Visualization Studio Comparison of the 2017 eclipse path and the 2024 eclipse path. A friend of mine was looking at the path of totality for the Great American Eclipse happening in a few days and noticed that it’s very different from the path of the 2017 eclipse. In 2017 it went from Oregon on the west coast down to South Carolina on the east. This year the eclipse traces a path from Mexico to Maine. The two paths cross in southern Illinois, and my friend wanted to know why. The answer has to do with the season in which each eclipse occurs. We experience seasons ..read more

NASA, ESA, K. Stapelfeldt (NASA JPL), G. Kober (NASA/Catholic University of America) The FS Tau multi-star system. We know how stars form. Clouds of interstellar gas and dust gravitationally collapse to form a burst of star formation we call a stellar nursery. Eventually, the cores of these protostars become dense enough to ignite their nuclear furnace and shine as true stars. But catching stars in that birth-moment act is difficult. Young stars are often hidden deep within their dense progenitor cloud, so we don’t see their light until they’ve already started shining. But new observations fro ..read more

Casey Reed, NASA Artistic image of a binary system of a red giant star and a younger companion that can merge to produce a blue supergiant. In the constellation of Orion, there is a brilliant bluish-white star. It marks the right foot of the starry hunter. It’s known as Rigel, and it is the most famous example of a blue supergiant star. Blue supergiants are more than 10,000 times brighter than the Sun, with masses 16 - 40 times greater. They are unstable and short-lived, so they should be rare in the galaxy. While they are rare, blue supergiants aren’t as rare as we would expect. A new study m ..read more

NASA, ESA, and D. Coe (NASA JPL/Caltech and STScI) Dark matter map in Galaxy Cluster Abell 1689. If you have a view of the southern celestial sky, on a clear night you might see two clear smudges of light set off a bit from the great arch of the Milky Way. They are the Large and Small Magellanic Clouds, and they are the most visible of the dwarf galaxies. Dwarf galaxies are small galaxies that typically cluster around larger ones. The Milky Way, for example, has nearly two dozen dwarf galaxies. Because of their small size, they can be more significantly affected by dark matter. Their formation ..read more

Avi Loeb/The Galileo Project A 0.4-millimeter diameter iron-rich spherule. Our solar system does not exist in isolation. It formed within a stellar nursery along with hundreds of sibling stars, and even today has the occasional interaction with interstellar objects such as Oumuamua and Borisov. So it’s reasonable to presume that some interstellar material has reached Earth. Recently Avi Loeb and his team earned quite a bit of attention with a study arguing that it had found some of this interstellar stuff on the ocean seabed.1 But a new study finds that the material has a much more local origi ..read more

NASA A pair of disc galaxies in the late stages of a merger. The Universe is filled with supermassive black holes. Almost every galaxy in the cosmos has one, and they are the most well-studied black holes by astronomers. But one thing we still don’t understand is just how they grew so massive so quickly. To answer that, astronomers have to identify lots of black holes in the early Universe, and since they are typically found in merging galaxies, that means astronomers have to identify early galaxies accurately. By hand. But thanks to the power of machine learning, that’s changing.1 With the po ..read more