NASA's Kepler hits big milestone with 1,000th exoplanet discovery

NASA's Kepler Space Telescope has recently hit a big milestone as it has discovered its 1,000th exoplanet.

The telescope continuously monitored more than 150,000 stars beyond our solar system, and to date has offered scientists an assortment of more than 4,000 candidate planets for further study, the 1,000th of which was recently verified.

Using Kepler data, scientists reached this millenary milestone after validating that eight more candidates spotted by the planet-hunting telescope are, in fact, planets. The Kepler team also has added another 554 candidates to the roll of potential planets, six of which are near-Earth-size and orbit in the habitable zone of stars similar to our Sun.

Three of the newly-validated planets are located in their distant suns' habitable zone, the range of distances from the host star where liquid water might exist on the surface of an orbiting planet. Of the three, two are likely made of rock, like Earth.

Both Kepler-438b and Kepler-442b orbit stars smaller and cooler than our Sun, making the habitable zone closer to their parent star, in the direction of the constellation Lyra.

With the detection of 554 more planet candidates from Kepler observations conducted May 2009 to April 2013, the Kepler team has raised the candidate count to 4,175. Eight of these new candidates are between one to two times the size of Earth, and orbit in their sun's habitable zone. Of these eight, six orbit stars that are similar to our Sun in size and temperature.

All candidates require follow-up observations and analysis to verify they are actual planets.

The study is published in the Astrophysical Journal Supplement.