Jupiter’s Great Red Spot has a disorderly counterpart that lurks in the planet’s high altitude thermosphere. Discovered by astronomers at Leicester University, the so-called Great Cold Spot spans thousands of miles and is thought to have formed from the planet’s spectacular auroras.
The lead astronomer behind the discovery, Dr Tom Stallard, described the Great Cold Spot as “more volatile” than the “slowly changing” Great Red Spot:
“It changes dramatically in shape and size over only a few days and weeks, but it has re-appeared for as long as we have data to search for it, for over 15 years.
“That suggests that it continually reforms itself, and as a result it might be as old as the aurorae that form it – perhaps many thousands of years old.”
The Great Cold Spot is at least 200 Kelvin cooler than the surrounding atmosphere, which ranges from 700 Kelvin (426C) and 1000K (726C)
The planet’s magnetic field forms polar auroras that drive heat around its atmosphere. Up in the thermosphere, at the boundary of space, this process causes cooling that is believed to drive the vortex now dubbed the Great Cold Spot.
The team used the Very Large Telescope in Chile to map the temperature and density of the planet’s atmosphere.
The astronomer added: “What is surprising at Jupiter is that, unlike weather systems on Earth, the Great Cold Spot has been observed at the same place across 15 years. That makes it more comparable to weather systems in Jupiter’s lower atmosphere, like the Great Red Spot.
“Observations and modelling of Earth’s upper atmosphere have shown that, on the short term, there may be changes in the temperature and density of the upper atmosphere.”
Facts about Jupiter:
Jupiter is a giant ball of gas 11 times wider than Earth and 300 times more massive. It takes 12 years for Jupiter to orbit the sun but rotates so quickly that a single day lasts just 10 hours.
Jupiter is sometimes said to have its own mini solar system. Its chemical composition is very similar to that of a star and its sheer size has attracted four large moons (Io, Europa, Ganymede and Callisto) and over 60 smaller objects known to be in orbit.
While you can’t normally see them, Jupiter also has a huge system of rings much like Saturn.