Astronomers have discovered a doomed planet that sheds a mass of material equal to Mount Everest every orbit, leaving behind a comet-like tail.

An illustration of a planet that is breaking apart while orbiting a giant star. (Photo credit: Jose-Luis Olivares, MIT)

Researchers have found a planet that is actually breaking apart as it orbits its star. About 140 light-years from Earth in the constellation Pegasus, the dying world, known as BD+05 4868 Ab, completes one orbit around its star every 30.5 hours — so close that its surface melts into magma and escapes into space.

With each rotation, BD+05 4868 Ab leaves behind a burning trail of molten rock, like a lava comet, providing a rare opportunity to observe an exoplanet in the final stages of its destruction. Even more astonishingly, with each 30-hour rotation, which heats the planet to nearly 3,000 degrees Fahrenheit (1,600 degrees Celsius), the planet loses the same amount of molten rock as the entire Mount Everest.

“The tail is enormous: it's about 9 million kilometers long, which is about half the entire orbit of the planet,” said Mark Hon, a postdoc at the MIT Kavli Institute for Astrophysics and Space Research.