22 degrees south of Jupiter’s equator, and at least 340 years old, a persistent anticyclonic hurricane roars with winds peaking above 400 mph.
The Great Red Spot (GRS) was first spotted in 1830, but observations from the 1600’s (such as Cassini in 1665) describe a spot on Jupiter that may or may not be the same storm system. The storm has been able to last this long on Jupiter due to the massive gas planet’s tens of thousands of miles of atmosphere, the fact that it spins much faster than Earth, and Jupiter’s 300-400 mph jet streams that surround either side of the GRS.
It’s dimensions 24-40,000 km by 12-14,000 km. Recent discoveries in 2017 made by the Juno spacecraft show that the storm is approximately 200 miles deep, 50-100 times deeper than Earth’s deepest ocean. This storm could fit 2 Earth-sized planets, as Jupiter does not have solid ground that the storm could slow down over. Only a massive sea of liquid hydrogen.
But the storm has been shrinking for a long time. Glenn Orton, a lead Juno Mission team member and planetary scientist at NASA’s Jet Propulsion Laboratory in California, said that, “The GRS will in a decade or two become the GRC (Great Red Circle), maybe sometime after that the GRM (Great Red Memory).” However, this is not new news. When the storm was first assuredly observed in the 1800’s, it was about 4 times the diameter of Earth. In 1979, when the Voyager 2 aircraft flew by Jupiter, the storm had shrunk down to a bit more than twice the width of our planet.
Scientists are still trying to learn more about the GRS. It is difficult to discern much information based on the Juno Spacecraft’s drive-by’s of the planet, as Jupiter is covered in a thick layer of gas that makes it difficult to determine what is at it’s surface or the conditions of it’s lower atmosphere. But recent discoveries have shown scientists another reason why the storm may have been raging for so long.
The Spot is warmer at the base of the storm than at the top. From the top, at the edge of Jupiter’s atmosphere, the storm measures at around -279 degrees Fahrenheit. Meanwhile, at its base, it measures 440 degrees Fahrenheit. This is an indication of the functioning of the hurricane because Jupiter’s weather physics and dynamics are incredibly similar to that of Earth, just millions and millions of miles further from the sun. Meaning that the temperature difference greatly drives winds, and provides an explanation not only to the GRS, but to all of the storms tearing across the gas giant.
But why is this important?
While it may not seem like that big of a deal, the GRS is actually integral to helping us understand planetary weather, resulting in further understanding of extrasolar (found in or taking place outside of the solar system) planetary cases. Amy Simon, an expert in planetary atmospheres at NASA’s Goddard Space Flight Center, said that “If you just look at reflected light from an extrasolar planet, you’re not going to be able to tell what it’s made of. Looking at many possible different cases in our own solar system could enable us to then apply that knowledge to extrasolar planets.” Understanding the GRS and how Jupiter’s weather system works could ultimately help us better understand planets even further away, and help us in our search for another Earth.
Sources:
https://www.nasa.gov/feature/goddard/jupiter-s-great-red-spot-a-swirling-mystery
https://www.space.com/39764-jupiter-great-red-spot-could-disappear.html
https://www.sciencedaily.com/terms/great_red_spot.htm
https://www.smithsonianmag.com/smart-news/what-lurks-below-jupiters-great-red-spot-180967524/