Cosmology

Hubble observations of a speedy galaxy weigh on the Milky Way and indicate that our galaxy is at least a trillion times as massive as the sun

Systematic searches are revealing a plenitude of alien worlds

Systematic searches are revealing a plenitude of alien worlds

At the driest place on Earth, one astronomer sifts through starlight to find clues about the Milky Way's evolution. Here is her account of a typical trip, based on four days in March 2011

NASA's MESSENGER orbiter has found evidence of pure water hiding near the planet's cool north pole

An eruption of matter from a quasar could show how galaxies shed weight

Experiments to detect dark matter, which scientists believe makes up about a quarter of the universe, are underway and may yield direct evidence within a decade

Thanks to gravitational lensing by a cluster of galaxies, the light emitted by a small galaxy 13.3 billion years ago has reached Earth. John Matson reports

Astronomers using the Subaru Telescope in Hawaii recently discovered ( pdf ) a "super-Jupiter" orbiting the star Kappa Andromedae (κ Andromedae) a star about 2.5 times the mass of our sun located about 170 light-years from Earth.

Long thought nearly extinct, the Andromedid meteor shower staged a surprise outburst last December—and may return in 2018 and 2023

The spiral, created by a red giant's companion star, lets astronomers see when layers of the red giant were lost