Mars, a world now circled by two lumpy rocks, may once have hosted a colossal companion that dominated its sky. New work on the planet’s tides, topography and wobbly interior points to a “lost” ...

Space is getting crowded — nowadays, over 45,000 human-made objects orbit Earth. A portion of that figure is indeed represented by the thousands of satellites humans use for internet, GPS and other ...

Mercury, Venus, Jupiter, Saturn, Uranus and Neptune will soon align in the night sky ...

The moon will pass directly in front of the sun on Feb. 17, setting the stage for a dramatic annular solar eclipse.

Using NASA's Fermi Gamma-ray Space Telescope, Chinese astronomers have observed a gamma-ray binary system known as PSR ...