This artist's concept shows a view across a mysterious disk of young, blue stars encircling a supermassive black hole at the core of the neighboring Andromeda Galaxy. The region around the black hole is barely visible at the center of the disk. The background stars are the typical older, redder population of stars that inhabit the cores of most galaxies.
The tip of the Boeing Delta II rocket with its MESSENGER spacecraft on top breaks through the billows of smoke below as it lifts off on Aug. 3, 2004 from Launch Pad 17-B at Cape Canaveral Air Force Station. MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) is on a seven-year journey to the planet Mercury. The spacecraft will fly by Earth, Venus, and Mercury several times to burn off energy before making its final approach to the inner planet on March 18, 2011.
At about 300 feet from the cargo bay of the space shuttle Challenger, Bruce McCandless II was farther out than anyone had ever been before. Guided by a Manned Maneuvering Unit (MMU), astronaut McCandless, pictured above, was floating free in space. McCandless and fellow NASA astronaut Robert Stewart were the first to experience such an 'untethered space walk' during Space Shuttle mission 41-B in 1984. The MMU works by shooting jets of nitrogen and has since been used to help deploy and retrieve satellites.
A collision between two galaxies has left one of them with a tail of stars, as revealed by an ultraviolet snapshot from a NASA space observatory.
Want to celebrate the 'birthday' of the Hubble Telescope? Here's 10 things that amateur astronomers can find (even without the Hubble Telescope).
Scientists have found that dark energy, the force thought to be accelerating the expansion of the universe, may be doing the same thing to local groups of galaxies. That bolsters Einstein's idea of a 'cosmological constant.'