Earth-sized planet covered in lava discovered by astronomers

(UPI) -- Astronomers have discovered a new exoplanet similar in size to Earth.

The new planet, dubbed Kepler-78b, has a radius just 1.17 times and a mass 1.9 times that of Earth. But the planet's proximity to its star -- 100 times closer than Earth is to the sun -- makes its surface temperature range from 2,240 to nearly 5,000 degrees Fahrenheit.

The lava planet was found around a star called Kepler 78 about 700 light-years from Earth. Astronomers made the discovery by watching the star dim as the planet passed in front of it, blocking its light.

The planet is a mystery given its proximity to its parent star. Kepler-78b orbits so close to the its star that it completes a full year every eight and a half Earth hours.

Known theories of planet formation don't permit a world to form at so close to its parent star. But mysterious exoplanets are popping up frequently enough to require additional theories.

NASA's Kepler space telescope has so far discovered over 130 worlds. Though a recent mechanical failure may have ended its planet-hunting mission, scientists are still hoping to salvage and repurpose Kepler for future use.