Kepler’s first planets
What happened: Kepler finds its first worlds When it happened: April 2009
Shortly after launching on 7 March 2009, Kepler spent 67 days in a commissioning phase, checking that its instruments worked to find distant worlds. It would do this by looking for the dip in light of distant stars as planets passed in front, known as the transit method, but scientists weren’t sure how successful this method would be.
In April 2009 it detected its first exoplanet, called TrES-2b. The planet, 1.2-times the size of Jupiter and 750 light years away, had been previously discovered, but Kepler’s detection of it proved the telescope would be able to find other planets, earning TrES-2b the additional moniker of Kepler-1b.
In August 2009 NASA announced Kepler had confirmed the existence of the known planet, HATP-7b, located 1,100 light years from Earth and about 1.5-times the size of Jupiter. Again a redetection, the sensitivity involved in finding this planet proved the telescope would be able find Earth-like worlds beyond the Solar System, if they existed. Following these initial detections Kepler would begin its primary mission in May 2009 lasting three-anda-half years, which changed the field of exoplanet science forever with the discovery of thousands of worlds, some of which were indeed Earth-like.
Kepler's field of view