The European Space Agency will launch an observatory into space designed to seek out potentially habitable planets outside of our solar system. The PLATO — Planetary Transits and Oscillations of stars — mission will search for planets by monitoring the brightness of up to a million nearby stars.

The mission will search for habitable planets

The space-based observatory will use 34 separate small telescopes and cameras to watch for tiny, regular drops in their targets' brightness: a sign that a planet is passing in front of the star. The ESA says the mission will have an emphasis on discovering and characterizing "Earth-sized planets and super-Earths" inside their parent star's habitable zone, which could potentially support the existence of both water and life. PLATO will also check for seismic activity in their target stars brought on by the orbit of their plants, and combine its data with radial velocity observations from here on Earth, allowing PLATO to measure any discovered planet's mass, radius, and density.

PLATO will launch on a Soyuz rocket from the ESA's main spaceport in French Guiana, and will orbit around the same point in space as the agency's star surveying craft, Gaia. The ESA says PLATO — the third medium class mission to be selected by the agency — will be in space by 2024, on a six-year mission. The other two medium-class missions selected so far, Solar Orbiter and Euclid, will launch in 2017 and 2020 respectively.