NASA Envisions Alien Worlds

Out of the Dust, a Planet is Born
In this artist's conception, a possible newfound planet spins through a clearing, detected around the star CoKu Tau 4 by the Spitzer Space Telescope, in a nearby star's dusty, planet-forming disc. The possible planet is theorized to be at least as massive as Jupiter, and may have a similar appearance to what the giant planets in our own solar system looked like billions of years ago.

Huygens on Titan
In 2005 the robotic Huygens probe landed on Titan, Saturn's enigmatic moon, and sent back the first ever images from beneath Titan's thick cloud layers. This artist's impression is based on those images. In the foreground, sits the car-sized lander that sent back images for more than 90 minutes before running out of battery power. The parachute that slowed Huygen's re-entry is seen in the background, still attached to the lander. Smooth stones, possibly containing water-ice, are strewn about the landscape. Analyses of Huygen's images and data show that Titan's surface today has intriguing similarities to the surface of the early Earth.

Steaming Hot Planet
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

Exoplanet HR 8799b
This is an artistic illustration of the giant planet HR 8799b.The planet was first discovered in 2007 at the Gemini North observatory. It was identified in the NICMOS archival data in a follow-up search of NICMOS archival data to see if Hubble had also serendipitously imaged it.The planet is young and hot, at a temperature of 1500 degrees Fahrenheit. It is slightly larger than Jupiter and may be at least seven times more massive. Analysis of the NICMOS data suggests the planet has water vapor in its atmosphere and is only partially cloud covered. It is not known if the planet has rings or moons, but circumplanetary debris is common among the outer planets of our solar system.

laring Red Dwarf Star
This is an artist's concept of a red dwarf star undergoing a powerful eruption, called a stellar flare. A hypothetical planet is in the foreground. Flares are sudden eruptions of heated plasma that occur when the field lines of powerful magnetic fields in a star's atmosphere "reconnect," snapping like a rubber band and releasing vast amounts of energy equivalent to the power of 100 million atomic bombs exploding simultaneously.Studying the light from 215,000 older red dwarfs collected in observations by NASA's Hubble Space Telescope, astronomers found 100 stellar flares popping off over the course of a week.

Fantastic Four Galaxies with Planet

This artist's concept shows what the night sky might look like from a hypothetical planet around a star tossed out of an ongoing four-way collision between big galaxies (yellow blobs). NASA's Spitzer Space Telescope spotted this "quadruple merger" of galaxies within a larger cluster of galaxies located nearly 5 billion light-years away.Though the galaxies appear intact, gravitational disturbances have caused them to stretch and twist, flinging billions of stars into space, nearly three times as many stars as are in our Milky Way galaxy. The tossed stars are visible in the large plume emanating from the central, largest galaxy. If any of these stars have planets, their night skies would be filled with the monstrous merger, along with other galaxies in the cluster (smaller, bluish blobs).This cosmic smash-up is the largest known merger between galaxies of a similar size. While three of the galaxies are about the size of our Milky Way galaxy, the fourth (center of image) is three times as big. All four of the galaxies, as well as most other galaxies in the huge cluster, are blob-shaped ellipticals instead of spirals like the Milky Way.Ultimately, in about one hundred million years or so, the four galaxies will unite into one. About half of the stars kicked out during the merger will fall back and join the new galaxy, making it one of the biggest galaxies in the universe.