THE NEW YORK TIMES - In six billion years the sun will expand into a red giant. That process should consume Mercury, and maybe Venus. For a long time we have thought it might incinerate Earth, too.
But perhaps all is not doomed for planet Earth (although it may be a world that will have long since become uninhabitable).
Scientists have discovered a rocky world orbiting another star that already went through its red giant phase. This planet now orbits a white dwarf, the smaller stellar body that remains after a star burns out. Crucially, the planet looks like it once orbited the star in the same position Earth currently travels around our sun, and did so until it was pushed to a more distant orbit, twice the Earth-sun distance, sometime before the dying giant could eat it. This makes it the first potential rocky world to be observed orbiting a white dwarf.
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Stephen Kane, an astronomer at the University of California, Riverside, said he was “really excited” when he saw the paper. However, Dr. Kane, who has previously investigated whether planets can survive a star’s red giant phase, said the presence of the brown dwarf posed complications. “If the brown dwarf was closer and then moved out, that changes the whole dynamical environment of the system,” he said. “Maybe there were other planets that were thrown out, and what we see is what survived.”