Near-infrared spectroscopic observations of the young extrasolar gas giant planet β Pictoris b indicate that it spins significantly faster than any planet in the Solar System. The new measurement continues a general trend, observed in our Solar System, of increasing spin velocity with planet mass. Although this relationship would predict a somewhat higher spin velocity for β Pictoris b, at about 50 kilometres per second rather than the observed 25, the authors note that the planet is still young and warm. With time it should cool and shrink, increasing the spin rate in the process.
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