An artists rendering image shows an exoplanet 6 times the Earth circulate around its low-mass host star at a distance equal to 1/20th of the Earth-Sun distance. European astronomers announced they had found 32 new planets orbiting stars outside our solar system on Monday. They believe their find means that 40 percent or more of Sun-like stars have such planets. The host star in this image is a companion to two other low-mass stars, seen in the distance. L. Calcada/ESO/Reuters
A view of the sun taken by 'Ahead,' one of NASA's twin Solar Terrestrial Relations Observatory (STEREO) spacecraft, is seen in this Sept. 26 photograph. The twin STEREO spacecraft, called 'Behind' and 'Ahead' denoting their relative positions in space, captured a large and dramatic prominence eruption over about a 30-hour period when the crafts were 120 degrees apart. Prominences, called filaments when they are viewed against the surface of the Sun, are clouds of cooler gas suspended above the Sun's surface by magnetic forces. NASA/REUTERS
This image of Neptune was taken during the August 16-17, 1989 period as Voyager 2 photographed the planet almost continuously. The image shows two of the four cloud features of the planet, which have been tracked by the Voyager 2, shown by the largest dark oval (l.) and the smaller oval in the lower right. NASA/AP/FILE
Astronomers reclassified Pluto as a dwarf planet at an International Astronomical Union meeting in Prague, Czech Republic, in August 2006. This image from the Hubble Space Telescope in 2005 shows Pluto, its moon Charon (below and right of center) and two newly discovered moons to the right. UPI Photo/NASA/NEWSCOM/FILE
The northern hemisphere of Venus is displayed in this global view of the planet's surface. The north pole is at the center of the image, which was produced at NASA's Jet Propulsion Laboratory (JPL) Multimission Image Processing Laboratory. Simulated color is used to enhance the image, which was recorded by the Soviet Venera 13 and 14 spacecraft. JPL/NASA/AP/FILE
This Oct. 6, 2008 image shows a portion of Mercury in previously unseen terrain, taken as the Mercury Surface Space Environment Geochemistry and Ranging spacecraft (MESSENGER) approached the planet. Heavily cratered terrain and a large, ancient, two-ring impact basic can be seen at the bottom center of the image. NASA-JHUAPL-CIW/CNP/NEWSCOM/FILE
A crescent moon (r.) is seen with the planet Jupiter in the sky over Amman, Jordan, December 1, 2008 – a rare astronomical phenomenon as two of the brightest naked-eye planets, Venus and Jupiter, join a thin crescent moon to create a brief 'unhappy face' in the sky. Ali Jarekji/Reuters
A gibbous moon is visible above Earth's atmosphere, photographed by a STS-128 crew member on the Space Shuttle Discovery on Aug. 30. A gibbous moon is one of the phases, between a first quarter moon and a full moon. The illuminated portion of the moon is greater than half, but not yet full. NASA/Reuters
Uranus's faint rings and several of its satellites are seen in this image taken with the Advanced Camera in August 2003. The planet's rings are made of dust and small pebbles. The bright satellite on the lower right corner is Ariel and five small satellites with dark surfaces can be seen just outside the rings. UPI Photo/NASA/NEWSCOM/FILE
This Sept. 9 image taken by the refurbished Hubble Space Telescope shows the planet Jupiter. NASA/AP
On the planet Mars, the sun sinks below the rim of Gusev crater in this May 2005 photo. Taken by NASA's Mars Exploration Rover Spirit, the Panoramic Camera (Pancam) mosaic was obtained using Pancam's three color filters, to allow false color images to be generated that are similar to what a human would see. Since Mars is further from the Sun than Earth, the Sun appears only about two-thirds the size that it appears in a sunset seen from Earth. Texas A&M/Cornell/JPL/NASA/Reuters/FILE
This false-color composite image is constructed from data obtained by NASA's Cassini spacecraft, shows the glow of auroras streaking out about 1,000 kilometers (600 miles) from the cloud tops of Saturn's south polar region, It was among the first images released from a study that identifies auroral emissions images taken by Cassini's visual and infrared mapping spectrometer. The composite image was made from 65 individual observations on Nov. 1, 2008. University of Leicester/University of Arizona/JPL/NASA/Reuters
Latin America and portions of Africa are seen in this photograph taken from the Apollo 11 spacecraft during its coast toward the moon in July 1969. NASA/AP/FILE
NASA's Kepler spacecraft has detected an Earth-sized planet orbiting an M dwarf star, scientists announced Thursday. We have some 70 billion M dwarf stars in our galaxy, so this suggests a huge number of potential life-friendly planets.
For the first time, astronomers have confirmed the presence of an Earth-sized planet orbiting another star in its "habitable zone" – the not-too-hot, not-too-cold region where a star warms a planet just enough to allow liquid water to form lakes or oceans. The planet, known as Kepler-186f, shares its star with four similar-sized planets that are all much closer to their sun and thus are too hot for liquid water on the surface.