Discover how a team of our scientists has uncovered evidence that Jupiter’s Great Red Spot is growing taller as it gets smaller.
Though once big enough to swallow three Earths with room to spare, Jupiter’s Great Red Spot has been shrinking for a century and a half. Nobody is sure how long the storm will continue to contract or whether it will disappear altogether.
A new study suggests that it hasn’t all been downhill, though. The storm seems to have increased in area at least once along the way, and it’s growing taller as it gets smaller.
Observations of Jupiter date back centuries, but the first confirmed sighting of the Great Red Spot was in 1831. But until then, researchers aren’t certain whether earlier observers who saw a red spot on Jupiter were looking at the same storm.
Amy Simon, an expert in planetary atmospheres at our Goddard Space Flight Center in Greenbelt, Maryland, and her team traced the evolution of the Great Red Spot, analyzing its size, shape, color and drift rate. They also looked at the storm’s internal wind speeds, when that information was available from spacecraft.
This new study confirms that the storm has been decreasing in diameter overall since 1878 and is now big enough to accommodate just over one Earth at this point. Then again, the historical record indicates the area of the spot grew temporarily in the 1920s. Scientists aren’t sure why it grew for a bit.
Because the storm has been contracting, the researchers expected to find the already-powerful internal winds becoming even stronger, like an ice skater who spins faster as she pulls in her arms.
But that’s not what is happening. Instead of spinning faster, the storm appears to be forced to stretch up. It’s almost like clay being shaped on a potter’s wheel. As the wheel spins, an artist can transform a short, round lump into a tall, thin vase by pushing inward with his hands. The smaller he makes the base, the taller the vessel will grow.
The Great Red Spot’s color has been deepening, too, becoming is a more intense orange color since 2014. Researchers aren’t sure why that’s happening, but it’s possible that the chemicals coloring the storm are being carried higher into the atmosphere as the spot stretches up. At higher altitudes, the chemicals would be subjected to more UV radiation and would take on a deeper color.
In some ways, the mystery of the Great Red Spot only seems to deepen as the iconic storm gets smaller. Researchers don’t know whether the spot will shrink a bit more and then stabilize, or break apart completely.
