Astronomers have discovered a planet as dense as diamond roughly 4,000 light-years away from Earth.
National Geographic reports that the unusual planet was discovered orbiting what's called a millisecond pulsar — "a tiny, fast-spinning corpse of a massive star that died in a supernova" — and that the diamond planet itself may have once been a star.
The millisecond pulsar, called PSR J1719-1438, lies in the southern constellation Serpens, closer to the center of the Milky Way than Earth.
A millisecond pulsar is thought to form when the pulsar is siphoning material from a companion star. The action of eating matter speeds up the pulsar's spin to hundreds of rotations a second.
PSR J1719-1438 is only the second known millisecond pulsars to have a planetary partner. And scientists believe the planet was formed from the remains of a white dwarf star, the core of a dead sunlike star, that has been stripped by the pulsar.
Scientists estimate that the planet is 34,175 miles across, and five times Earth's diameter. The planet orbits the pulsar in just two hours and 10 minutes, covering a distance of 372,822 miles.
"The evolutionary history and amazing density of the planet all suggest it is comprised of carbon — i.e. a massive diamond orbiting a neutron star every two hours in an orbit so tight it would fit inside our own Sun," study leader Matthew Bailes, of Swinburne University of Technology, said, according to Reuters.
Reuters reports that the planet has slightly more mass than Jupiter but is 20 times as dense — denser, in fact, than any other known planet. But scientists don't yet know what the diamond planet might look like. It was found by detecting modulations in the beams of radiation being emitted by the pulsar. The modulations were caused by the gravitational pull of the planet.
"In terms of what it would look like, I don't know I could even speculate," Ben Stappers of the University of Manchester told Reuters. "I don't imagine that a picture of a very shiny object is what we're looking at here."