Great Red Spot visible for 200 years
When you see the dark and light stripes next to each other on Jupiter, it’s actually winds blowing in opposite directions. When this happens, they can spin large cyclones, just as when playing beach ball, pushing the ball with one hand and pulling with the other hand will make it spin. Humans have been observing the Great Red Spot for at least 200 years and it is accompanied by strong winds almost the entire time.
Like all hurricanes, it can change from day to day. Sometimes round and sometimes it looks like an egg. Its color can also change from brownish-reddish to light red. Sometimes it looks almost white. But recently scientists have noticed the shrinking of this huge cyclone. About 100 years ago, the Great Red Spot was about three times larger than it is today.
Why is Jupiter’s storm shrinking?
To understand why it is shrinking, it helps to first understand why cyclones on Earth shrink and eventually stop. On Earth, cyclones often form over deep, warm oceans before moving onto hard land or cold water. When cyclone winds hit hard land, the winds slow down and hence the cyclone slows down. Cyclones on Earth are also affected by other seasons and the winds around them, which can ‘damp’ the cyclone in a matter of days.
But Jupiter does not have a hard, rocky surface like Earth. And even though the air in Jupiter’s clouds is extremely cold, the air inside is very warm. This warm air gives storms plenty of energy to wreak havoc for months, or even years. So while the Great Red Storm is shrinking. It might actually still be a bit long and there’s plenty of energy to keep moving around.
Great Red Spot can break into small storms
We can also see it weakening at the edges as it slips into other storms and the winds around it. But astronomers still don’t know if it will stop completely. Some think that it could break up into several smaller storms one day. Recently, the Juno space probe (which has been orbiting Jupiter since 2016) took many beautiful pictures of Jupiter’s storms while flying by the planet. We can learn something new from these pictures. Until then, we can admire the Great Red Spot as long as it is active.