Astronomers find extreme weather on an alien world

Astronomers have observed extreme brightness changes on a nearby brown dwarf that may indicate a storm grander than any seen yet on a planet. Because old brown dwarfs and giant planets have similar atmospheres, this finding could shed new light on weather phenomena of extra-solar planets.

The scientists used an infrared camera on the 2.5m telescope at Las Campanas Observatory in Chile to capture repeated images of a brown dwarf dubbed 2MASS J21392676+0220226, or 2MASS 2139 for short, over several hours. In that short time span, they recorded the largest variations in brightness ever seen on a cool brown dwarf.

The planet’s brightness changed by a whopping 30% in just under eight hours. The best explanation is that brighter and darker patches of its atmosphere are coming into our view as the brown dwarf spins on its axis. This might be a gigantic storm raging on this brown dwarf, perhaps a grander version of the Great Red Spot on Jupiter in our own solar system, or it could be the hotter, deeper layers of its atmosphere through big holes in the cloud deck.