"Scientists at a Japanese university said Thursday they believed another planet up to two-thirds the size of the Earth was orbiting in the far reaches of the solar system.

The researchers at Kobe University in western Japan said calculations using compute ... Read More »

A NASA comet probe heading back to Earth for a gravity boost will be redirected after the disappearance of its intended target.

Deep Impact, which won funding for an extended mission after its successful close-up studies of Comet Tempel 1 in 2005, was expected to ... Read More »

Just when space scientists thought they had solved the mystery of the brightest explosions in the universe, along comes one that has the experts befuddled.

The confounding "gamma ray burst" was detected by space-based instruments and the Swift or ... Read More »

A comet targeted for a flyby with NASA's Deep Impact spacecraft cannot be found, forcing mission planners to send the probe to a different comet. The comet may have evaded telescopes simply because its predicted orbit was incorrect, or, more intriguingly, it might have disintegrated complet ... Read More »