Astrophysics

Astronomers suspect that there’s a large planet hiding out in the distant fringes of the solar system. At a recent workshop, they brainstormed ways to coax it into view.

Astronomers have found stars dating from a long-ago collision between the Milky Way and another galaxy. The crash helps to explain why the Milky Way looks the way it does.

Computer simulations have become so accurate that cosmologists can now use them to study dark matter, supermassive black holes and other mysteries of the real evolving cosmos.

The inventors of a “Swiss army knife” for genome editing received prestigious honors, as did pioneering scientists in astrophysics and neuroscience.

Detailed images of disks swirling around young stars show the details of how solar systems come to be.

Astronomers argue that there’s an undiscovered giant planet far beyond the orbit of Neptune. A newly discovered rocky body has added evidence to the circumstantial case for it.

A roundup of some of the most important discoveries gleaned so far from the Gaia space observatory’s new map of the galaxy.

Two ways of measuring the universe’s expansion rate yield two conflicting answers. Many point to the possibility of new physics at work, but a new analysis argues that unseen errors could be to blame.

New observations of extreme astrophysical systems have “brutally and pitilessly murdered” attempts to replace Einstein’s general theory of relativity.