Astronomers discover an Earth-sized planet with an 8.5 hour year

Researchers from MIT have located a lava-filled world about 700 light-years away that's 40 times closer to its star than Mercury is to our sun. It's considered one of the shortest orbital periods known to science.

Kepler 78b is a planet that spins around its sun every 8.5 hours. Its orbital radius is ridiculous — a mere three times the radius of the star itself — and its surface temperature could be as high as 3,000 degress Kelvin (5,000 degrees Fahrenheit). Subsequently, the top layer of Kepler 78b is probably completely melted, creating one big swooshing ocean of lava.

Needless to say, this is not a habitable world.

Astronomers discover an Earth-sized planet with an 8.5 hour yearS

Illustration by Ron Miller

Kepler 78b is so close to its sun that astronomers will try to measure its gravitational influence on the star.

Previously, astronomers have observed KOI 1843.03, another exoplanet that features an orbital period of 4.25 hours. It's about half the size of Earth. Astronomers speculate that, in order for it to maintain its extremely tight orbit, it has to be incredibly dense, probably made out of iron. Otherwise, the tidal forces would rip it to shreds.

Read the entire paper at The Astrophysical Journal: "Transits and Occultations of an Earth-sized Planet in an 8.5 hr Orbit."

Top Image: Cristina Sanchis