Illustration of Kepler-452b

Kepler is an orbiting space telescope launched in 2009. It searches distant stars for Earth-like planets within a solar system's "habitable zone," an area around a star that maintains a temperature range moderate enough to allow liquid water to exist on a planet's surface. 

In 2013 two of Kepler’s four reaction wheels, which pointed the spacecraft, failed. Efforts to fix them were unsuccessful, and data collection ceased. In 2014 Kepler began a new mission. Using pressure from sunlight, mission scientists can control the spacecraft's position again, and its hunt for planets has resumed.

This artist concept is of Kepler-452b, the most similar expoplanet to Earth found to date. It orbits in the habitable zone of star similar to our Sun. Kepler-452b is about 60 percent larger than Earth and orbits its star every 385 days. The star has nearly the same temperature and mass as our Sun.