sciencehabit (1205606) writes "What do you do if you're a hot Jupiter and want to cool off? Why, you use your gravity to lift up the surface of your sun, cooling it and creating a dark spot on the star. In a forthcoming issue of The Astrophysical Journal Letters, astronomers will report using the Kepler spacecraft to observe the brightness of a star in the constellation Cygnus more than a million times. Named HAT-P-7, this star has a hot Jupiter—a giant planet orbiting close-in —which other scientists found before NASA launched the spacecraft. The world's gravity raises the star's surface away from its hot center, causing part of the surface to cool by just a fraction of a degree Kelvin and produce a dark spot that lags behind the planet's position by a few hours. If confirmed, this discovery is the first time astronomers have ever seen planet-induced "gravity darkening" and demonstrates Kepler's remarkable ability to detect even the subtlest of stellar signals."
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