The largest planet in our solar system, Jupiter, apart from its gigantic size, is widely recognized for its Great Red Spot, a raging storm twice the diameter of Earth. But as astronomers have recently uncovered, the Great Red Spot isn't the lone highlight in the gas giant's surface.
There's also apparently a Great Cold Spot, which has just been discovered. Researchers first noticed the Great Cold Spot via the Very Large Telescope in Chile, but to confirm its existence, they had to look at observations culled from other telescopes in a 15-year period.
Great Cold Spot Discovered On Jupiter
The spot, stretching up to 15,000 miles across and 7,500 miles wide, is mostly defined by its cooler temperature than that of the area surrounding it in the planet's upper atmosphere. Typically, temperatures in the planet's upper atmosphere range from about 700 to 1,000 Kelvin; the spot is 200 Kelvin cooler.
What's causing the Great Cold Spot is yet to be determined by planetary scientists, although it's worth noting that Jupiter's atmosphere itself remains as much of a mystery. An area of localized cooling in Jupiter's upper atmosphere is, according to the authors of a new study, "unexpected."
The findings were published in Geophysical Research Letters, conducted by a team of astronomers led by Tom Stallard, an associate professor in planetary astronomy at the University of Leicester in the United Kingdom.
The researchers, however, are proposing a theory: that the Great Cold Spot's existence is thanks to the planet's nearby auroras, which drive energy into the atmosphere and in turn cause heat flows around the planet. But such a correlation remains to be discussed, as Jupiter's auroras are themselves complex, caused by a great many effects and processes.
Is There A Great Cold Spot On Earth, Too?
Interestingly, Stallard says that there is evidence that could point to a similar phenomenon on our own home planet. Our auroras, however, are so much more variable, so while a vortex does appear and disappear intermittently, such changes occur only over the course of a few hours, appearing then wilting fast.
The spot's changes are vastly different in terms of timescale, often distorting and sometimes almost disappearing completely in the 15-year span of data observed.
The Age Of Jupiter's Great Cold Spot
In astronomers' observations, the Great Cold Spot disappears from time to time, but when it resurfaces, there are notable changes in its position and morphology. The authors surmise that it's likely the spot signals a weather system that's been regenerated repeatedly in the past, "for as long as Jupiter has had its northern magnetic field asymmetry."
The exact length of time this signifies is hard to determine, but in contrast with slow pace of change within the Earth's magnetic field, it's possible that the Great Cold Spot has "existed for thousands of years, and perhaps much longer."
All told, it was a surprise for the researchers to discover the Great Cold Spot, and they will resume investigation while perusing for evidence of other atmospheric features. Earth-based observations, coupled with findings from the Juno spacecraft currently orbiting the planet, should provide more information about Jupiter's weather.
