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AR 2192, the largest sunspot seen since the beginning of the current 11-year cycle that started in 2008, is producing strong solar flares.

A "mountain-sized" comet known as Siding Spring will pass very close to the red planet, where orbiters from the U.S., Europe and India, hope to get close — but not too close — to the action.

There are many theories about what exactly the unmanned X-37B is doing as it circles the Earth on long-duration missions.

"For the first time in modern history, the eastern basin of the South Aral Sea has completely dried," NASA says, citing satellite photos from 2000 and 2014.

A U.S. probe cost $637 million to get to Mars; an Indian mission cost about a tenth as much. There are at least a few reasons why, both teams agree — starting with the differing shapes of each orbit.

The orbital probe will study how the solar wind interacts with the red planet's thin atmosphere.

Scientists hope NASA's MAVEN probe, which went into orbit Sunday night, will provide insight into why the Martian climate changed drastically billions of years ago.

Earlier this week, NASA awarded two contracts for new spaceships to commercial companies. Here's how they compare.

By 2017, the two American companies are expected to take over a job that NASA has relied upon Russia to perform: shuttling astronauts to the International Space Station.

NASA needs Russian rockets to reach the International Space Station, and Russia needs NASA's money to help finance operations.

For the past decade or so, scientists have been waiting for the Voyager 1 spacecraft to cross into deep space. New research suggests it already has — over a year ago.