Why Does Jupiter Have the Great Red Spot?
Written by Fraser Cain
Jupiter is beautiful to look at, both in a backyard telescope and with the Hubble Space Telescope. Even in the smallest telescope you can see atmospheric bands across the planet, and its 4 largest moons orbiting around it. With larger telescopes you can see the famous Great Red Spot – a swirling storm larger than the Earth.
Astronomers have been observing the Great Red Spot for more than 300 years, so it's incredibly long lasting. But it is changing. In 2004, the Great Red Spot was only half the size it was a century earlier, reaching a total size of 40,000 km. At this current rate, astronomers think it will become circular by 2040.
Thanks to recent missions to Jupiter, like Galileo, Cassini and New Horizons, scientists are learning a tremendous amount about how the atmosphere on Jupiter works.
Hot gases in Jupiter's atmosphere are constantly swirling around, rising and falling. As cooler gas falls down through the atmosphere, the Coriolis force causes the region to start swirling. These eddies can last for a long time because there is no solid ground on Jupiter to create friction.
These eddies can move around and merge into one another, creating larger and larger storms, which last for longer periods. According to theories, several of these larger storms came together, combining their energy to create the long lived Great Red Spot.
We can see this process happening again with another spot on Jupiter called Oval BA. It was first discovered a few years ago when three white storms merged together. This new "Red Spot Jr." has been stable in the atmosphere of Jupiter for more than 6 years now. It and the larger Red Spot have even passed each other several times now, and not caused much damage.
Scientists think the Great Red Spot has its characteristic red color because the strength of the storm is digging down into Jupiter's atmosphere, bringing complex organic molecules to the high atmosphere.
Filed under: Astronomy
