

This is an artist's concept of a gas giant planet orbiting the cool, red dwarf star Gliese 876, located 15 light-years away in the autumn constellation Aquarius. The planet was discovered in 1998. But new Hubble Space Telescope measurements of the star's wobble, caused by the gravitational tug of the planet, firmly establish the planet's mass as being no more than approximately twice that of Jupiter's.
This is an image of one-half of the Hubble Space Telescope field of view in the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS). The field is so crowded with stars because Hubble was looking across 26,000 light-years of space in the direction of the center of our galaxy. Half of these stars are bright enough for Hubble to monitor for any small, brief and periodic dips in brightness caused by the passage of an exoplanet passing in front of the star, an event called a transit.
This artist's concept depicts the pulsar planet system discovered by Aleksander Wolszczan in 1992. Wolszczan used the Arecibo radio telescope in Puerto Rico to find three planets - the first of any kind ever found outside our solar system - circling a pulsar called PSR B1257+12. Pulsars are rapidly rotating neutron stars, which are the collapsed cores of exploded massive stars.
This artist's concept shows what a fiery hot star and its close-knit planetary companion might look close up if viewed in infrared light. In infrared, a star is less blinding, and its planet perks up with a fiery glow. Astronomers using NASA's Spitzer Space Telescope took advantage of this fact to directly capture the infrared light of two previously detected planets orbiting outside our solar system. Their findings revealed the temperatures and orbits of the planets.
Astronomers have discovered the most Earth-like planet outside our Solar System, pictured in an artist's rendering, an exoplanet with a radius only 50% larger than the Earth and capable of having liquid water, announced by the Eupropean Southern Observatory on April 25, 2007. Using the ESO 3.6-m telescope, a team of Swiss, French and Portuguese scientists discovered the planet about 5 times the mass of the Earth that orbits a red dwarf, already known to harbor a Neptune-mass planet.
This is an artist's impression of the gas-giant planet orbiting the yellow, Sun-like star HD 209458, 150 light-years from Earth. Astronomers used NASA's Hubble Space Telescope to look at this world and make the first direct detection of an atmosphere around an extrasolar planet. The planet was not directly seen by Hubble. Instead, the presence of sodium was detected in light filtered through the planet's atmosphere when it passed in front of its star as seen from Earth.
This artist's impression shows a dramatic close-up of the scorched extrasolar planet HD 209458b in its orbit 'only' 7 million kilometers from its yellow Sun-like star.
This artist's concept depicts an extrasolar planet with hypothetical (possible but unproven) water-bearing moons.
This artist's concept from 2003 shows an extremely far away exoplanet. The planet, in the constellation Sagittarius, whizzes around its star every 29 hours and is shrouded in clouds made not of water droplets but of iron atoms. This is a world of iron rain.
This NASA artist's concept image obtained May 24, 2010 shows that the hottest known planet in the Milky Way galaxy may also be its shortest-lived world. The doomed planet is being eaten by its parent star, according to observations made by a new instrument on NASA's Hubble Space Telescope, the Cosmic Origins Spectrograph (COS). The planet may only have another 10 million years left before it is completely devoured.
A team of astronomers, led by Frederic Pont from the Geneva University Observatory in Switzerland, has detected for the first time strong evidence of hazes in the atmosphere of a planet orbiting a distant star. The new Hubble Space Telescope observations were made as the extrasolar planet, dubbed HD 189733b, passed in front of its parent star in an eclipse. As the light from the star briefly passes through the exoplanet's atmosphere, the gases in the atmosphere stamp their unique spectral fingerprints on the starlight.
Scientists have reported the first conclusive discovery of water vapor in the atmosphere of an exoplanet, or a planet beyond our solar system. This artist's impression shows a gas-giant exoplanet transiting across the face of its star. Infrared analysis by NASA's Spitzer Space Telescope of this type of system provided the breakthrough. The planet, HD 189733b, lies 63 light-years away in the constellation Vulpecula. It was discovered in 2005 as it transited its parent star, dimming the star's light by some three percent.
This still from an animation portrays an artist's concept of a distant hypothetical solar system, about the same age as our own. Though extrasolar planets are too small to be seen with telescopes, astronomers have detected more than 100 gas giants like Jupiter via their gravitational tug on their parent stars.
This is an artist's impression of a unique type of exoplanet discovered with the Hubble Space Telescope. The planet is so close to its star that it completes an orbit in 10.5 hours. The planet is only 750,000 miles from the star, or 1/130th the distance between Earth and the Sun. The Jupiter-sized planet orbits an unnamed red dwarf star that lies in the direction of the galactic center; the exact stellar distance is unknown.
This is an artist's concept of a Jupiter-mass planet orbiting the nearby star Epsilon Eridani. Located 10.5 light-years away, it is the closest known exoplanet to our solar system. The planet is in an elliptical orbit that carries it as close to the star as Earth is from the Sun, and as far from the star as Jupiter is from the Sun.