NASA’s Kepler space telescope’s count of exoplanets has passed the magic 1,000 mark, including eight new "habitable" planets and 544 candidate planets. The latest tally is based on Kepler’s observations of 150,000 stars in the constellation of Lyra, from which the Kepler team and others have identified 4,175 candidate exoplanets and have confirmed 1,000.
Until its primary mission was ended due to a reaction wheel malfunction, Kepler hunted for exoplanets by means of the transit method. That is, it would scan a predesignated area of the sky and measure the light coming from various stars. If a planet passed between the star and Kepler, the result would be a dip in the stars brightness. By recording the curve of the light intensity and making precise calculations, it is possible to determine if a planet is indeed the cause and deduce various characteristics of it, such as orbit and size.
One major find among the new planets are eight that are no more than twice the size of Earth and orbit in their stars’ habitable zones, where the temperatures are in the region that allows liquid water to exist on the planet’s surface. Of these eight, six orbit stars similar to the Sun, and of these, two are probably rocky terrestrial planets like those of the inner Solar System.