Extreme and irregular variations in the brightness of a nearby brown dwarf suggest the star's atmosphere is wracked with storms. Using data gathered by an infrared camera during a
survey of such stars, astronomers have found that the brightness of a brown dwarf—dubbed 2MASS 2139, which lies about 47 light-years from Earth—varied as much as 30% in less than 8 hours. That radical variation could be best explained by brighter and darker patches of its cloudy atmosphere (see
image) rotating into view as the star spins on its axis, the researchers contend. Or, as they will report later this week at the Extreme Solar Systems II conference in Jackson Lake, Wyoming, it's possible that bright spots
represent brief glimpses of deep, hot layers of atmosphere through dark clouds composed of silicate and metallic dust grains. If the variations are
caused by massive storms similar to those that occasionally rage on Jupiter and Saturn, then the storms are larger than any yet discovered on a planet.
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