Scientists discover 'featherweight' planet with an 8-hour year

If it feels like time flies when you're on Earth, just imagine visiting exoplanet GJ 367b.

Amanda Kooser
Freelance writer Amanda C. Kooser covers gadgets and tech news with a twist for CNET. When not wallowing in weird gear and iPad apps for cats, she can be found tinkering with her 1956 DeSoto.
Amanda Kooser
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Exoplanet GH 367b stars in this artist's illustration. A whole year lasts just 8 hours on the planet.

SPP 1992 (Patricia Klein)

What's in a year? On Earth, 365 days. On planet GJ 367b, only 8 hours. The exoplanet (one that's located outside our own solar system) is a speed demon when it comes to orbiting its star. An entire year would pass in the time it takes you to get a good night's sleep.

GJ 367b is likely a rocky planet rather than a gas planet like Jupiter or Saturn. "It seems to have similarities to Mercury. This places it among the sub-Earth sized terrestrial planets and brings research one step forward in the search for a 'second Earth,'" said astronomer Kristine Lam in a German Aerospace Center (DLR) statement on Thursday.

Lam is the lead author of a paper on the extrasolar planet published in the journal Science on Thursday. The study features 78 authors, highlighting just how much of a collaboration the research was.  

DLR described the planet as a "featherweight" with half the mass of Earth, making it one of the lightest known exoplanets among the nearly 5,000 on record so far. It's a little bigger than Mars by diameter and can be found just 31 light-years from Earth. 

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The intriguing exoplanet was discovered in data from NASA's Transiting Exoplanet Survey Satellite (TESS) using the transit method, where scientists look for a telltale dimming of a star when a planet passes in front of it. GJ 367b orbits a red dwarf star, a type that is smaller and cooler than our own. 

While GH 367b seems like it might be a fun planet to ride on, it would be a pretty miserable place to visit. That short year means it orbits very close to its star and gets blasted with radiation while experiencing surface temperatures that could melt rock and metal. 

The planet represents a step forward in scientists' understanding of these distant worlds. "The discovery demonstrates that it is possible to precisely determine the properties of even the smallest, least massive exoplanets," said DLR. "Such studies provide a key to understanding how terrestrial planets form and evolve."