Jupiter’s Great Red Spot has company. Meet the Great Cold Spot

Aurora may fuel colder mark in planet’s northern atmosphere

Jupiter's cold spot

SPOTTED  Jupiter’s northern aurora, shown in this Hubble Space Telescope image, may help generate the newly detected “Great Cold Spot” in the planet’s atmosphere.

J. Nichols/University of Leicester, NASA, ESA

Jupiter’s got a second giant spot.

Called the Great Cold Spot, this dark mark is twice as big as Earth, but cooler and more fickle than the planet’s famous (and similarly sized) Great Red Spot. The cool spot sits in Jupiter’s northern regions, not far from the stunning northern aurora in the planet’s atmosphere. The aurora may play a role in creating the newly detected dark mark, researchers report online April 10 in Geophysical Research Letters.

“We can’t be exactly sure how the spot forms,” says study coauthor Tom Stallard, a planetary scientist at the University of Leicester in England. “But we are sure it is there because we observed it numerous times.”

Stallard and colleagues got their first clue that the Great Cold Spot existed when they used the Very Large Telescope in Chile to study an ion of hydrogen in Jupiter’s atmosphere. While mapping the atmosphere’s temperature and density, the team discovered a region about 73 degrees Celsius cooler than the gas around it. Comparing the data with observations from the NASA Infrared Telescope Facility in Hawaii revealed that the dark mark had actually been seen in the same location for more than 15 years.

Jupiter's cold spot, animated
SEEING SPOTS The shape and size of the Great Cold Spot (dark patch in center) changed dramatically between 1998 and 2000. This animation, generated from images taken with the NASA Infrared Telescope Facility in Hawaii, shows those changes from the perspective of a satellite orbiting Jupiter at a distance of 35,000 kilometers. T. Stallard/University of Leicester
Though the mark shows up in the same place, its size and shape changes. “Sometimes it is clearly a spot,” Stallard says, “and sometimes it’s not so prominent.” Such shape-shifting may arise because the cool spot is tied to the influx of energetic particles into Jupiter’s atmosphere from the Jovian moon, Io, showers which help generate auroras. On Earth, auroras can produce vortices in the upper atmosphere that are cooler than the surrounding gas. The Great Cold Spot may be a similar kind of swirling weather system that waxes and wanes as the intensity of Jupiter’s northern aurora changes.

“To see weather in this region of the atmosphere is weird,” says Planetary Science Institute researcher Jeffrey Morgenthaler, who is based in Maine. Researchers thought the temperature contrasts caused by the aurora would get smoothed out quickly, he says, so finding such a long-lived vortex in the upper layers of the atmosphere is unexpected.

Ashley Yeager is the associate news editor at Science News. She has worked at The Scientist, the Simons Foundation, Duke University and the W.M. Keck Observatory, and was the web producer for Science News from 2013 to 2015. She has a bachelor’s degree in journalism from the University of Tennessee, Knoxville, and a master’s degree in science writing from MIT.

More Stories from Science News on Planetary Science