Kepler

Kepler, named after Johannes Kepler, is a spacecraft launched by the U.S. The objective of Kepler's mission is to detect exosolar planets, or planets outside our system.

The Kepler spacecraft consists of a large telescope, equipped only for observing subtle signs of planets. The telescope will detect transits, or slight eclipses of light from the star when a planet passes in front. Some of these light changes are so slight that the difference in brightness is equal to that of a fly on a windshield, but Kepler will detect them all the same.

The Kepler spacecraft was launched on March 7, 2009 from Cape Canaveral, Florida. It escaped Earth's orbit and settled into its orbit around the Sun, which causes Kepler to follow Earth around its orbit. Kepler went through a commissioning phase and began observation on May 13, 2009. Then, the first information was transmitted to Earth in June. NASA will sorts through the thousands of images to find signs of exosolar planets. In September, Kepler verified the existence of an exosolar planet. The planet's orbital period is just over two days, so Kepler took under a week to detect its transit three times.

On January 12, 2010, the first five new planets were discovered from an analysis of the results obtained in November of the previous year. On August 26, 2010, three additional planets orbiting the same star were announced. Another major discovery occurred in early 2011, when a system of six planets was announced, along with the smallest extrasolar planet yet discovered. Planet discoveries continued to trickle in as the year went on, including another planet in May 2011.

Another interesting discovery was that of a planet, named Kepler-16b, orbiting a binary star system. Discovered in September 2011, it is the first definitively confirmed circumbinary (circum = around, binary = two [stars]) planet. Also, in November 2011, Kepler-21b was discovered. It is a rocky planet only 60% massive than Earth. Unfortunately, it is so close to its parent star that it orbits in less than three days.

On January 26, 2012, 26 new planet discoveries were released, including two more instances of circumbinary planets, and numerous systems containing two or more planets, leading to higher estimates of planets per star in the Milky Way. In response to this unexpected bounty of planets, NASA extended the mission of Kepler through 2016 in April 2012. This allowed the confirmation of orbiting bodies with longer periods of revolution. Other significant discoveries of 2012 include the first known occurrence of two planets orbiting two stars.

By 2013, Kepler had discovered over 100 planets.