"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 computer simulations led them to conclude it was only a matter of time before the mysterious "Plan ... 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 use its Dec. 31 flyby of Earth for a slingshot maneuver to rendezvous with a comet known as 85P/Boet ... 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 orbiting gamma ray observatory on Jan. 25, 2007. At first it stood out only because it was rather brig ... 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 completely.

The Deep Impact spacecraft completed its main mission in 2005, when ... Read More »

A rare new kind of star may have been discovered. It is much like the white dwarf our own sun should eventually become—save for a mysterious shroud of carbon ash.

The findings could shed light on the life and death of stars, astronomers said.

After they exhaust all their nuclear fuel, more than 97 percent of the stars in our ... Read More »

A ragged company of stars is rushing through the chaotic core of our galaxy, travelling faster than can easily be explained. The new measurement of its orbit, made with the 10-metre Keck telescope in Hawaii, US, also deepens a mystery surrounding the Milky Way's central black hole.

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Astronomers have found nine of the faintest, tiniest and most compact galaxies ever seen. Read More »