For years, astronomers have predicted a dramatic fate for our galaxy: a head-on collision with Andromeda, our nearest large galactic neighbor. This merger—expected in about 5 billion years—has become ...

Israeli astronaut Ilan Ramon had a question before going into space: How would he mark Sabbath, the Jewish day of rest, from orbit? Sabbath begins Friday at sunset and ends Saturday after sunset. But ...

“Megaconstellations” of vast numbers of satellites could threaten space-based astronomy, scientists have warned.