Astrophysics

A problem confronts cosmology: Two independent measurements of the universe’s expansion give incompatible answers. Now a third method, advanced by an astronomy pioneer, appears to bridge the divide.

A recent neutron star merger has defied astronomers’ expectations, leading them to question longstanding ideas about neutron stars and the supernovas that create them. “We have to go back to the drawing board.”

By watching for a special kind of flare, astronomers have identified the fingerprints of an Earth-size planet orbiting a distant star.

As astronomers get better at finding the comets and asteroids of other stars, they’ll learn more about the universe and our place in it.

Physicists saw a black hole for the first time, debated the expansion rate of the universe, pondered the origin of time and modeled the end of clouds.

After a space telescope disintegrated, astrophysicists had little hope of understanding how supermassive black holes agitate giant galaxies. Then they invented a hack.

How a young celebrity became one of the first female astronomers at Caltech, befriended Richard Feynman, and ended up the world’s foremost chronicler of the science of the night sky.

Most every cosmologist believes the universe is flat. A new analysis argues that it’s closed.

How do magnetars get so magnetic? A study of stellar explosions shows that the long-accepted theory might be wrong.