About 1,700 extrasolar planets have been discovered so far, including 715 discoveries that were announced in February, 2014 by the National Aeronautical and Space Administration. The newest extrasolar planets were discovered when astronomers examined 305 stars with Kepler, NASA's first extrasolar planet mission. Extrasolar planets, also called exoplanets, are planets that exist outside of the solar system.
Extrasolar planets revolve around their own stars in the same fashion that the planets revolve around the sun. NASA's findings show that most extrasolar planets are located within systems that contain multiple planets orbiting a star. Some extrasolar planets are even thought to have habitable conditions similar to those on Earth.
According to NASA, the first extra-solar planet was discovered in 1994 by Dr. Alexander Wolszczan, a Pennsylvania State University astronomer. Wolszczan discovered an extrasolar planet that orbits a dying star, or pulsar. In 1995, a planet orbiting a true star, like the sun, was discovered by Michel Mayor and Didier Queloz. By the end of the 20th century, Mayor and Queloz's discovery was followed by the identification of dozens of other extrasolar planets. Besides NASA's Kepler mission, the French CoRoT mission has been an important tool in the discovery of many extrasolar planets.