Photographs taken of Mercury by the spacecraft MESSENGER were analyzed in the journal Science. Images like the one above show that volcanic activity played a part in forming plains on the planet.
For years, astronomers have been baffled by the source of antimatter. Now, researchers say the matter-annihilating material is generated when stars get ripped apart by black holes or neutron stars. In this image from NASA's Spitzer Space Telescope, thousands of stars swirl around the super massive black hole at the center of the Milky Way.
Even galaxies get bullied. Here, a so-called "death star galaxy" blasts a nearby galaxy with a jet of energy. Scientists said that if this happened in the Milky Way, it would likely destroy all life on Earth.
Feel like you are being watched? This infrared image from NASA's Spitzer Space Telescope shows the Helix nebula, a cosmic starlet notable for its vivid colors and eerie resemblance to a giant eye.
The Cassini spacecraft's 2005 flyby of Saturn's moon Hyperion revealed its sponge-textured surface. This image was colored to bring out the surface's details. Hyperion has a notably reddish tint when viewed in natural color.
This star is ending its life by casting off its outer layers of gas, forming a cocoon around the star's remaining core. The burned-out star, called a white dwarf, is the white dot in the center.
Here, bright blue newly formed stars are blowing a cavity in the center of a star-forming region and eroding the outer portions of the nebula, with numerous galaxies delivering a grand backdrop for the stellar newcomers.This small open star cluster lies in the core of the large emission nebula in Sagittarius, about 8,000 light-years away from Earth. Some of the stars in this cluster are extremely massive and emit intense ultraviolet radiation.
Radar data from NASA's Magellan craft helped scientists stitch together this image of Venus. A European probe recently detected evidence of lighting inside the clouds of sulfuric acid that compose Venus' dense atmosphere.
This is one of the largest panoramic images ever taken with Hubble's cameras, a 50-light-year-wide view of the central region of the Carina Nebula where a maelstrom of a star's birth and death is taking place.
These are views of an unusual phenomenon called a light echo. Light from an erupted star continues outward through a cloud of dust surrounding the star. The light reflects or "echoes" off the dust and then travels to Earth.
This eerie-looking Eagle Nebula, a tall, dense tower of gas, is one of three-quarters of a million photos of the cosmos taken by the Hubble Telescope.
This image of the Whirlpool Galaxy is one of the sharpest Hubble has ever produced. The telescope has orbited the Earth for 15 years and has taken more than 700,000 images of the cosmos.
This is one of the universe's most photogenic galaxies, the Sombrero Galaxy. Its hallmark is a brilliant white, bulbous core encircled by thick dust lanes comprising the spiral structure of the galaxy.
Resembling the fury of a raging sea, this is actually a bubbly ocean of glowing hydrogen gas and small amounts of other elements such as oxygen and sulfur within the Omega or Swan Nebula.
This dramatic shot of the Orion Nebula offers a peek inside a cavern of roiling dust and gas where more than 3,000 stars are forming.
The Crab Nebula is a six-light-year-wide expanding remnant of a star's supernova explosion. Japanese and Chinese astronomers witnessed this violent event in 1054.
This nebula is the glowing remains of a dying, sun-like star. This stellar relic is called the Eskimo Nebula because, when viewed through ground-based telescopes, it resembles a face surrounded by a fur parka.
A pair of huge interstellar "twisters" -- eerie funnels reminiscent of terrestrial tornadoes -- are seen in the heart of the Lagoon Nebula about 5,000 light-years from Earth.
The Red Square is among the most symmetrical objects ever observed. It was created by a dying star spewing its innards from opposite poles into space.
Close-up photos reveal rising crater walls that tower over the floors below. The spacecraft also investigated Mercury's magnetic field. Earth and Mercury are the only planets in the inner solar system that have magnetic fields, though Earth's is much stronger.
This image of an ultraviolet flash of light was produced from a dying star just before it exploded. It marked the first time scientists observed what happened in the final moments before a doomed star burst into space.