This exoplanet might literally be the most metal planet out there

Enlarge / Computer-generated conception of the hot, metal planet. (credit: NASA)

Metals are everywhere in the Universe, from hot gas giants where it rains molten iron to heavy elements formed as a star goes supernova. Exoplanet GJ 367b one-ups them all. This planet is made of metal.

GJ 367b is an extreme planet. This “super Mercury,” which orbits its star once every 7.7 hours, was first discovered by NASA’s TESS planet hunter in 2015. Now, scientists from the University of Turin in Italy and the Thüringer Landessternwarte in Germany have examined more recent measurements of the planet using ESO’s HARPS spectrograph along with the original TESS observations. They found that this object is almost twice as dense as Earth—which suggests it is most likely made of solid iron.

Even though GJ 367b is now a solid iron planet, it might have once been the core of an ancient rocky planet.