Xena, the possible 10th planet in our solar system, has its own moon, a dim little satellite called Gabrielle, its discoverers say. Astronomers who reported Xena's discovery in July say they detected ...

LOS ANGELES – A distant, icy rock whose discovery shook up the solar system and led to Pluto's planetary demise has been given a name: Eris. The christening of Eris, named after the Greek goddess of ...

PASADENA, Calif.–The International Astronomical Union (IAU) today downgraded the status of Pluto to that of a “dwarf planet,” a designation that will also be applied to the spherical body discovered ...

Xena, unofficially called the 10th planet, is the second-most-shiny known object in the solar system, new observations show. Scientists are scrambling to explain where Xena got its sparkle. Some ...

Astronomers said on Saturday that they spotted a moon orbiting what they insisted to be the 10th planet of our solar system. Mike Brown, an astronomer at the California Institute of Technology, said ...

The International Astronomical Union has announced that the dwarf planet known as Xena since its 2005 discovery has been named Eris, after the Greek goddess of discord. Eris's moon will be known as ...

The planet - a giant lump of rock and ice, more than nine billion miles from the Sun - is the first to be discovered since Pluto in 1930. The breakthrough will cause the redrawing of the maps of our ...

The dwarf planet formerly known as Xena received a new name Thursday, while Pluto was given a number to reflect the loss of its status as a planet. Michael Brown, a professor of planetary astronomy at ...

Los Angeles | Our solar system is suffering an identity crisis. For decades, it has consisted of nine planets, even as scientists debated whether Pluto really belonged. Then the recent discovery of an ...

The heated debate over what constitutes a planet has reignited following last week’s confirmation that the most distant planet-like object object ever seen in the solar system is larger than Pluto.

Xena, the possible 10th planet in our solar system, has its own moon, a dim little satellite called Gabrielle, its discoverers say. Astronomers who reported Xena's discovery in July say they detected ...