It’s one of the most unusual, distinctive and beautiful features of our solar system’s gas giant: the huge red spot south of Jupiter’s equator that’s been captivating astronomers for hundreds of years. It’s a powerful storm, but its time may be waning. Observations and measurements show that the Great Red Spot, as it’s known, is shrinking, and has been doing so since at least the 1800s. Recent observations by Hubble and other high-quality telescopes suggest the spot is actually getting smaller even more rapidly than before.
The Great Red Spot is an example of an anticyclonic storm, with winds flowing opposite the direction predicted under the Coriolis effect. They’re typically seen in areas of high pressure and while they run contrary to an observed and understood scientific phenomenon, they aren’t freaks of nature, but the result of special interactions between warm and cold fronts. Using infrared imaging, scientists have discovered that the Great Red Spot is, despite the color, a cold spot, and it sits above the surrounding clouds.
For observers, the Great Red Spot is a compelling sight. But it might not be around much longer. In a recent shot, the Hubble took a photo indicating that the Great Red Spot was smaller than ever before, about 10,250 miles across. 35 years ago, it was 14,500 miles across, and in the 19th century, it was 25,500 miles across. This suggests not only that the Great Red Spot is becoming, well, less great, but also that the rate of shrinkage is stepping up.
Has the Great Red Spot lost critical mass? This is a tricky question to answer, in part because we don’t really understand this storm very well in the first place. Despite the fact that it may have been going for 400 years or longer, giving us ample opportunities to research it and learn more about it, much more research and energy has been sunk into the atmospheres of other planets, like Venus. As the spot shrinks, it’s more imperative than ever to find out more about how Jupiter’s atmosphere works and what caused it. This may give us insight into the other long-lived spots that drift across the planet’s surface, and into why the Great Red Spot eventually collapsed.
Natural factors on the planet? Climate change occurring over time as a result of changes on Jupiter’s surface? The Great Red Spot has been known to absorb lesser storms, which change its dynamics, and this may be playing a role here. Researchers definitely believe the storm is shrinking, not being covered by higher cloud cover, because of the changes in shape being observed — this would seem to suggest that the actual structure of the storm is shifting in response to something, even if we can’t see it.
Even with shrinkage, the Great Red Spot is still big enough to swallow Earth whole, a few times over. But that may not always be the case. Scientists interested in the fate of the storm theorize that it’s not having a major effect on the planet, but they still want to learn more about it on the grounds of pure curiosity.
While understanding Jupiter’s weather won’t help us fix our own climate problems, it may enhance our comprehension of the universe and how planets become habitable or fall short of the mark.
Photo credit: NASA Goddard Space Center