The spot is likely a tall methane cloud that reaches high enough for us to see sunlight scattered by its icy particles, said Uranus expert Heidi Hammel, executive vice president of the Association of Universities for Research in Astronomy (AURA).
The Uranian cloud is probably similar to an anvil cloud, the type of towering cumulonimbus cloud (picture) that’s associated with severe thunderstorms on Earth.
The cloud is also at a lower latitude on Uranus than any that have been observed before. That could mean the spot is a storm that has migrated south.
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Extraterrestrial Hurricanes: Other Planets Have Huge Storms, Too
Hurricane Irene is a monster storm on Earth. But it’s just a baby compared to the massive cyclones of Jupiter and Saturn
Our planet is not the only one in the solar system that boasts huge, hurricane-like storms. The gas giants Jupiter and Saturn, for example, churn out spinning squalls that can be bigger than the entire Earth. While these storms aren’t fed by warm ocean water the way terrestrial hurricanes are, they’re similar in a lot of ways, scientists say.
“There certainly are storms that have thunder and lightning and rain that are bigger than terrestrial hurricanes,” said atmospheric scientist Andrew Ingersoll of the California Institute of Technology, a researcher with NASA’s Cassini mission to Saturn. “And more violent — the winds on those planets are stronger, too.”
Giant Planets, Giant Storms
Hurricane Irene measured about 600 miles (966 kilometers) across as it bore down on the U.S. East Coast today (Aug. 26).
That’s big and scary, but it pales next to storms on our solar system’s gas giants. Jupiter’s Great Red Spot — which has been raging continuously for at least 180 years — could fit two entire Earths within it, Ingersoll said.
And in December, a thunderstorm about 6,200 miles (10,000 km) wide erupted on Saturn. This one, known as the Great White Spot, is still going strong, and some of its clouds have wrapped all the way around the ringed planet.
