NASA's Juno spacecraft flew over Jupiter's Great Red Spot twice and saw what it saw

NASA held a news conference this week revealing the agency's surprising latest findings on Jupiter, including how deep the Great Red Spot really is and how "resilient" cyclone storms are.

The Great Red Spot is a massive anticyclonic storm that has existed for a long time 22° south of Jupiter's equator, the largest planet in the solar system. Since 1830, it has been continuously observed for 189 years.

At a news conference, Scott Bolton, chief investigator of NASA's Juno mission and director of space science and engineering at the Southwestern Institute in San Antonio, said people thought the Great Red Spot was a storm that looked like a flat "pancake."

"We know it lasted a long time, but we don't know how deep it is or how it works." Bolton said at a news conference.

In February and July 2019, NASA's Juno spacecraft flew directly over the Red Spot twice to figure out the depth of its vortex under the visible cloud tops of the Great Red Spot, about 10,000 miles (16,000 kilometers) wide. Two papers published Thursday in the journal Science detail Juno's findings.

Scientists had thought that the depth of the Great Red Spot Storm was limited to the depth at which sunlight could penetrate or where water and ammonia were expected to condense, the height of the planet's clouds. However, the researchers found that the storm was not so shallow.

With the help of a microwave radiometer aboard the Juno spacecraft, scientists made three-dimensional observations of Jupiter. They found that the Great Red Spot was between 124 miles (200 kilometers) and 311 miles (500 kilometers) deeper than expected, extending into the depths of the gas giant.

Marzia Parisi, a research scientist at NASA's Jet Propulsion Laboratory in Pasadena, California, said: "The Great Red Spot is as deep inside Jupiter as the international space above our heads. ”

The Great Red Spot is remarkably deep-rooted, but the team found that it was still shallower than the latitudinal jets that powered the storm, which were nearly 1,864 miles (3,000 kilometers) deep.

While the Great Red Spot Storm continues to rage, its size is shrinking. In 1979, the Great Red Spot was twice the diameter of the Earth. Since then, its size has shrunk by at least a third.

A tough polar cyclone

Five years ago, scientists used image data collected by Juno to learn more about Jupiter's poles.

Juno discovered that the gas giant had five cyclonic storms in the Antarctic, in the shape of a pentagon, and eight cyclonic storms in the Arctic, forming an octagon.

Five years later, when Juno observed the cyclones using Jupiter's Infrared Aurora Mapper, it was found that the storms were still in the same position.

The explanation for this phenomenon is that when polar cyclones try to move toward the poles, cyclones at the top of each pole push backwards one by one. Pushing and pulling, it caused the polar storm to "stand still".

Since 2016, the Juno spacecraft, as wide as a basketball court, has been orbiting Jupiter, scanning the atmosphere and mapping its magnetic and gravitational fields.