A new study using data from NASA’s Hubble Space Telescope finds that star formation in the nearby Andromeda galaxy has undergone a 500-million-year decline, with an even steeper drop in the last 40 million years. Andromeda, a spiral galaxy comparable in size to our Milky Way, is close enough to be seen with the unaided eye from areas with dark skies. Located about 2.5 million light-years from Earth—practically our cosmic backyard—Andromeda offers an opportunity for astronomers to examine its stellar populations in detail, leading to a better understanding of the past of galaxies like our own.

Mercury was long considered the exception to the rule that magnetic planets have radiation belts similar to Earth’s Van Allen belts, but a new study by University of Michigan Engineering and the University of California, Berkeley, suggests otherwise—Mercury occasionally has such a layer of radiation in its magnetic field.

“Dead stars” known as white dwarfs have already shown the potential to help us better understand how planetary systems, including our own solar system, take shape and evolve. Now, research from the University of Michigan and the University of Colorado Boulder suggests that potential could be even greater than anticipated.

A team of astronomers at the University of North Carolina at Chapel Hill has observed an extremely rare “wandering” black hole located tens of thousands of light-years from the center of its galaxy. This finding could reshape scientists’ understanding of how massive black holes move through the universe after galaxies collide. The findings are published in The Astrophysical Journal Letters.

Positrons—the antimatter counterpart of electrons—are created in high-energy cosmic processes. When normal matter meets its antimatter counterpart, they annihilate, or vanish, and produce a distinctive 511 keV gamma-ray signal. Scientists use this signal to detect where these annihilations occur.