Our Milky Way Galaxy rotates 15 percent faster and is twice as massive as formerly believed — making it an equal match for the Great Andromeda Galaxy rather than its little brother.

Professional and amateur astronomers around the world are gearing up for a year-long celebration of understanding and enjoying the cosmos.

In 2014, if construction goes as planned, Chinese astronomers will begin to probe distant cosmic targets with the world's largest single-aperture radio telescope.

Once again an intrepid team of scientists and other adventurers is combing the ice fields of Antarctica for meteorites. Follow the searchers on their quest — and learn about the leaders who return for a cold soak year after year — by reading the team's daily weblog.

An international team of observers has found an alien world where the temperature is always a toasty 4,600°F and it takes just a second or two to get a great suntan.

On December 15, 2008, planetary science lost one of most gifted and passionate practitioners — a radar astronomer whose work greatly improved our knowledge of near-Earth asteroids.

The universe just isn't making galaxy clusters the way it used to. Compelling new evidence argues that "dark energy" has overwhelmed gravity's influence on forming these largest cosmic structures.

For the first time since 2005, the world's official timekeepers will add an extra second to the clock on New Year's Eve.

436-year-old light echoes give a look today at a blast in the Renaissance past. The catch? They're only a twenty-billionth as bright as the original.

Astronomers report that a planet circling a star 63 light-years away in Vulpecula is wreathed in an atmosphere containing water vapor.

Testing has begun on the first of 18 mirror segments for NASA's James Webb Space Telescope, the gargantuan craft that will join the aging Hubble in space as early as 2013 — and eventually replace it as NASA's premier space observatory.

NASA managers have decided on a date to dispatch Space Shuttle flight STS 125, the final servicing mission to the Hubble Space Telescope.

Plagued by a technical obstacles that could threaten its success, a $2 billion Mars rover has been postponed two years by NASA officials. The Mars Science Laboratory's new launch date is 2011.

Periodic Comet Machholz 1 has such a unique composition that a researcher suggests it may have come from another solar system. Though the odds against this seem long.