An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of 771 such planets (in 617 planetary systems and 102 multiple planetary systems) have been identified as of June 2, 2012. Estimates of the frequency of systems strongly suggest that more than 50% of Sun-like stars harbor at least one planet.
Astronomers have made a crude two-dimensional thermal map of an extrasolar world they cannot yet see, confirming that violent winds rapidly whip around the planet.
GJ 1214b is not exactly Earth’s twin: It’s about six times bigger, a whole lot hotter and made mostly of water. But compared to the giant gas balls that account for nearly every other extrasolar planet ever found, it’s pretty darn close. And through a fortunate happenstance of cosmic geometry, astronomers will be able to study GJ 1214b in great detail.
The first Earth-sized planets orbiting a Sun-like star outside the Solar System have at last been detected. The discovery paves the way to finding Earth-like worlds.
The sun-like star, called HD 10180, is located approximately 127 light-years away from Earth. In a previous study that was published in August 2010, astronomers identified five confirmed alien worlds and two planetary candidates.
For centuries, theories of planet formation were guided exclusively by our solar system. However, the discovery of planets orbiting other stars (exoplanets) has demonstrated that nature often produces planetary systems quite different from our own, neither anticipated by nor well explained by the current theories of solar system formation and dynamics.
In 1992 scientists first detected a planet outside our Solar System, orbiting a pulsar. A few years later, the planet 51 Pegasi B was found orbiting a star similar to the Sun. Hundreds of these extrasolar planets, or exoplanets, have been found since.
For centuries, many philosophers and scientists supposed that extrasolar planets existed, but there was no way of knowing how common they were or how similar they might be to the planets of the Solar System. Various detection claims made starting in the nineteenth century were all eventually rejected by astronomers.
Astronomers have taken what they say are the first-ever direct images of planets outside of our solar system, including a visible-light snapshot of a single-planet system and an infrared picture of a multiple-planet system.
Most extrasolar planets (or exoplanets for short) can't be seen directly, especially if they are very close to their parent stars; astronomers see only the combined light of the star and the planet. Sometimes, they happen to see the orbits of exoplanets edge-on.
Exoplanets or Extrasolar Planets are planets that orbit distant stars. At least 100 Extrasolar Planets (exoplanets) have been found in other Star Systems, but they cannot be seen visually. These planets vary from Jupiter-like planets that orbit much closer to their star than our Planet Mercury to giant planets that have orbits beyond our Planet Pluto in distance from their star.
NASA’s Kepler mission has discovered 11 new planetary systems hosting 26 extrasolar planets. According to NASA’s Jet Propulsion Laboratory, these planets range in size from 1.5 times the radius of Earth to giants larger than Jupiter. All of them are closer to their host star than Venus is to our Sun.