Photo Gallery: Planet Hunting
This is an artist's conception of the smallest planet found outside our solar system to date. The Neptune-sized planet orbits a star named Gliese 436, which is about four-tenths the size of our sun. Gliese 436 is depicted as reddish because it is cooler than our sun. The new planet orbiting Gliese 436 circles the star every 2.6 days.
In this artist's concept of one of the newfound planets, the Neptune-sized planet circles the star known as 55 Cancri, which is similar in size to our sun. The innermost of four planets orbiting 55 Cancri at a distance of 3.5 million miles, the planet's temperature is estimated to be at least 2,700 Fahrenheit. The 55 Cancri system is the first known four-planet system, located 41 light-years away in the constellation Cancer.
This graphic shows what the planetary system around star 55 Cancri might look like, beginning with its giant outermost planets. The recent discovery of a Neptune-sized planet near the star makes 55 Cancri the first star outside our sun known to support four planets.
The star 55 Cancri is about 5 billion years old and a little lighter in weight than our own sun.
This illustration from NASA shows the size of the planets discovered orbiting other stars outside our solar system. Most exoplanets discovered thus far have been gassy giants around the size of Jupiter, but the most recent findings have uncovered smaller planets the size of Neptune, pictured in the middle as either gaseous (the larger blue silhouette) or rocky (the smaller pink silhouette).