One year on Earth-sized exoplanet lasts 8.5 hours

MIT researchers discovered an Earth-sized exoplanet named Kepler 78b that spins around its host star in a short 8.5 hours. (Cristina Sanchis Ojeda)

Imagine if you got a full night's sleep or completed a single workday to discover an entire year just flew by? Researchers at MIT found an Earth-sized exoplanet that spins around its host star in a mere 8.5 hours, completing a year's worth of activity.

In comparison, it takes our planet roughly 8765.81 hours, or 365 days, to orbit the sun.

"We've gotten used to planets having orbits of a few days," an associate professor of physics at MIT Josh Winn said in a press release. "But we wondered, what about a few hours? Is that even possible? And sure enough, there are some out there."

700 light-years from the Earth, exoplanet Kepler 78b has one of the shortest orbital periods ever discovered. Researchers who observed the planet found that it reached surface temperatures above 5,000 degrees Fahrenheit.

At such a high temperature, it is likely the top layer of the planet is melted, creating a turbulent ocean of lava.

"Just the fact that it’s able to survive there implies that it's very dense," Winn explained. "Whether nature actually makes planets that are dense enough to survive even closer in, that's an open question, and would be even more amazing."

8.5 hour days are not in the future, as Kepler 78b's proximity to its host star makes it inhabitable.

"You'd have to really stretch your imagination to imagine living on a lava world," Winn said. "We certainly wouldn't survive there."

The researchers reported their discovery of Kepler 78b in The Astrophysical Journal.