Juno Probe Reveals Jupiter’s Great Red Spot Extends 200 Miles Deep
The Juno space probe was launched back in 2011 on course for Jupiter. It arrived in orbit of the gas giant in summer 2016 after five years of travel, and it began sending back stunning images and extensive scientific data early this year. One of the primary duties of Juno is to study the iconic Great Red Spot, a giant cyclone that has been churning in Jupiter’s clouds for centuries. A newly released study based on Juno data includes the most accurate measurements yet of this monster storm.
Scientists have long wondered how deep the Great Red Spot goes, and now we know thanks to Juno. Data returned by the probe shows that the roots of the vortex extend about 200 miles (321 kilometers) into the planet’s atmosphere. By comparison, Earth only has about 60 miles of atmosphere before you get to space.
The examination of the Great Red Spot’s interior took place during the probe’s first pass over it in July 2017. The probe’s microwave radiometer scanned below the outer visible layer, finding the clouds get colder the closer they are to the surface. Higher temperatures are associated with higher wind speeds, which explains the rapidly rotating vortex visible in the upper cloud layers.
Radiation around the gas giant has already put a damper on Juno’s plans. After an engine error, NASA opted not to tighten the probe’s orbit as originally intended. That would have exposed it to more radiation that could exacerbate problems. So, Juno remains in a 53-day orbit of Jupiter. It takes longer to complete each observation, but it won’t encounter as much radiation. That’s probably good as the spacecraft has detected two new bands of radiation that NASA didn’t know about when designing Juno. These newly discovered regions are above the equator and in the mid-latitudes. They both consist of hydrogen, oxygen and sulfur ions moving at close to the speed of light. These atoms might be falling down on Jupiter from the moons Io and Europa.
Reliable records of the Great Red Spot stretch back to the early 1800s, but astronomers from the late 17th century may also have seen evidence of the spot’s existence. One way or the other, it’s old, but it’s also been shrinking. The Great Red Spot today is 10,000 miles across (16,000 km), just a third as large as it was in the 1970s. It’s possible this distinctive feature could continue shrinking and vanish completely in the coming decades. That’s why Juno’s mission is so vital. The probe will pass over Jupiter again this coming Sunday, December 16th.