Imagine a storm, larger than Earth, raging in the atmosphere of a gas giant planet. It sounds like science fiction, but such an atmospheric phenomenon does exist on the planet Jupiter. It's called the Great Red Spot, and scientists believe it has been orbiting Jupiter's cloud masses since the mid-1600s.
Humans began observing the current spot in 1830, using telescopes and spacecraft for this purpose. NASA's Juno spacecraft came too close to this area, orbiting Jupiter, and captured several high-resolution images of the planet and the storm surrounding it. Photos like these give scientists a fresh look at one of the oldest known storms and reveal some of the secrets that exist in the solar system.
What is the Great Red Spot?
The Great Red Spot gives an idea of the magnitude of this massive storm on the largest planet in the solar system.
Technically, the Great Red Spot is an anticyclonic storm that lies in a high pressure zone in Jupiter's clouds. It rotates counterclockwise and takes about six Earth days to complete one complete trip around the planet. It features clouds that often extend for miles above the surrounding cloud decks. The north and south jet streams help maintain the position at the same latitude as the circulation.
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The Great Red Spot is indeed red, although chemical reactions in the clouds and the atmosphere cause a color change, making it more pinkish orange than red. Jupiter's atmosphere is mostly a mixture of molecular hydrogen and helium, but there are other chemical compounds we know of: water, hydrogen sulfide, ammonia, and methane. The same chemicals are found in the clouds of the Great Red Spot.
No one really knows exactly why the colors of the Great Red Spot change over time. Planetary scientists suspect that solar radiation is causing the chemicals in the Spot to darken or lighten, depending on the intensity of the solar wind. Jupiter's cloud belts and zones are rich in these chemicals and are also home to many small storms, including white ovals and brown spots floating among swirling clouds.
Research of the Great Red Spot
When 17th-century astronomers first turned their telescopes toward Jupiter, they noted a prominent reddish spot on the giant planet. This formation is still present in Jupiter's atmosphere after 300 years.
Observers have studied the gas giant planet Jupiter since antiquity. Nevertheless, they have been able to observe such a gigantic spot for several centuries since its first discovery. Ground-based observations allowed scientists to map out its movement, but a true understanding of the phenomenon became possible only during flights of spacecraft. The Voyager spacecraft flew in 1979, during which the first large-scale photograph of the slick was taken.
The shape of the spot will change
Throughout the research, scientists have learned more about the rotation of the spot, its movement through the atmosphere, and evolution. Some astrophysicists suspect that its shape will continue to change until it is nearly round. Perhaps this will happen in the next 20 years.
This resizing is significant. For many years, the slick was larger than two cross-pieces of the Earth. When the Voyager spacecraft was launched in the 1970s, it shrank by only two Earths. Now it is 1.3 and is constantly decreasing.
Astronauts photographed the largest storm on Jupiter from the spacecraft Juno
A high-resolution image of a large-scale red spot was delivered by the Juno spacecraft in 2017. This image revealed details in the clouds swirling around in a giant anticyclone. The spacecraft also measured the temperature near the site, as well as its depth.
The spacecraft Juno was launched in 2015 and began orbiting Jupiter in 2016. It flew low and close to the planet, reaching only 3400 kilometers above the clouds. This allowed astronauts to observe some incredible detail in the Great Red Spot.
Scientists were able to measure the depth of the spot using special instruments. It appears to be at a depth of about 300 kilometers. This is a greater indicator than the depth of any of the Earth's oceans. It is just over 10 kilometers long.
Hurricanes on Jupiter
Interestingly, the "roots" of the Great Red Spot are warmer at the bottom than at the top. This heat feeds on the incredibly strong and fast winds in the upper part of the sunspot, which can blow at speeds of over 430 kilometers per hour. Warm winds feeding a violent storm are a well-understood phenomenon on Earth, especially during massive hurricanes. Above the clouds, temperatures are rising again, and scientists are trying to understand why this is happening. In this sense, the Great Red Spot is the source of the hurricanes that Jupiter experiences.
Maya Muzashvili