It's remarkably similar to Earth.

Our solar system may have a ninth planet after all, researchers say. The possibility that an additional planet may be hidden far into the solar system was touted more than a century ago. But ...

A newly identified Earth-sized exoplanet with a year-long orbit may lie near its star’s habitable zone, but extreme cold could limit its chances of hosting liquid water.

Ask someone on Earth for the time and they can give you an exact answer, thanks to our planet's intricate timekeeping system, built with atomic clocks, GPS satellites and high-speed telecommunications ...

A faint signal from old telescope data is causing a stir in astronomy: a planet barely larger than Earth, with an almost ...

Astronomers have found a planet that orbits at an angle of 90 degrees around a rare pair of peculiar stars. This is the first time we have strong evidence for one of these 'polar planets' orbiting a ...

Astronomers have found thousands of exoplanets around single stars, but few around binary stars—even though both types of stars are equally common. Physicists can now explain the dearth.