This artist's conception shows a hypothetical planet with two moons orbiting in the habitable zone of a red dwarf star. Using publicly available data from NASA's Kepler space telescope, astronomers at the Harvard-Smithsonian Center for Astrophysics estimate that six percent of red dwarf stars have an Earth-sized planet in the "habitable zone," the range of distances from a star where the surface temperature of an orbiting planet might be suitable for liquid water.
The majority of the sun's closest stellar neighbors are red dwarfs. Researchers now believe that an Earth-size planet with a moderate temperature may be just 13 light-years away.
Astronomers don't know if life could exist on a planet orbiting a red dwarf. However, this finding suggests that the most common type of the star in the galaxy may provide many more cosmic neighborhoods to search for planets that may be like our own.
An artist's conception, of a "hot Neptune" known as Kepler-36c as it looms in the sky of its neighbor, the rocky world Kepler-36b.
The two planets have repeated close encounters, experiencing a conjunction every 97 days on average. An odd pair of distant worlds -- one rocky like Earth and another gassy like Neptune -- have been found doing the closest dance of any planetary pair ever discovered.
The duo are orbiting their star about 1,200 light years from Earth, and were discovered with NASA's Kepler space telescope. Their star is probably a lot like our Sun but several billion years older, and the planets are much closer to it, said the study in Science Express.
This artist’s rendering provided by NASA shows the Kepler space telescope. NASA is calling off all attempts to fix Kepler but it’s not quite ready to call it quits on the robotic planet hunter. The space agency is looking at what science might be salvaged by using the broken spacecraft as is.
This artist rendition obtained from NASA shows planets the size of Saturn orbiting a distant star.
Astrophysicists using the Kepler space telescope have detected two planets the size of Saturn and a possible third the size of Earth orbiting a distant star, a report published August 26, 2010, said. The new solar system discovered by the Kepler telescope is about two thousand light years from Earth.
This photo shows an artist's impression of the Kepler-47 solar system in which at least two planets orbit around two stars. Using NASA's Kepler space telescope, a team of astronomers has found the first transiting circumbinary multi-planet system: two planets orbiting around a pair of stars.
This planetary system is located roughly 5000 light-years away from Earth, in the constellation of Cygnus (The Swan).
The outer planet's orbit places the planet well within what astronomers refer to as the habitable zone, the region around a star within which a terrestrial planet that could have liquid water on its surface might be found.
This NASA artist's animation depicts an ultra-dense dead star, called a white dwarf, passing in front of a small red star. As the white dwarf crosses in front, its gravity is so great that it bends and magnifies the light of the red star.
NASA's planet-hunting Kepler space telescope was able to detect this effect, called gravitational lensing, not through direct imaging, but by measuring a strangely subtle dip in the star's brightness.
The red dwarf star is cooler and redder than our yellow sun. Its companion is a white dwarf, the burnt-out core of a star that used to be like our sun. Though the white dwarf is about the same diameter as Earth, 40 times smaller than the red dwarf, it is slightly more massive. The two objects circle around each other, but because the red dwarf is a bit less massive, it technically orbits the white dwarf.
Kepler is designed to look for planets by monitoring the brightness of stars. If planets cross in front of the stars, the starlight will periodically dip. In this case, the passing object turned out to be a white dwarf not a planet. The finding was serendipitous for astronomers because it allowed them to measure the tiny "gravitational lensing" effect of the white dwarf, a rarely observed phenomenon and a test of Einstein's theory of relativity. These data also helped to precisely measure the white dwarf's mass.
This image made by the Kepler telescope and released by NASA shows a 100-square-degree patch of sky in the Milky Way galaxy. NASA is calling off all attempts to fix the crippled space telescope.
United Launch Alliance's Delta II rocket carrying NASA's Kepler space telescope rises on March 6, 2009 through the exhaust cloud created by the firing of the rocket’s engines.