Clouds on Jupiter run surprisingly deep

PASADENA, Calif. — Jupiter’s clouds have deep roots. These aerial bands of color wrap around the planet. They also extend down deeply into its atmosphere. That’s one of the new discoveries by NASA’s Juno spacecraft. It has been providing an unprecedented peek into the giant planet’s interior.

Scott Bolton works at the Southwest Research Institute in San Antonio, Texas. He is also head of NASA’s Juno mission. “Whatever’s making those colors and stripes still exists pretty far down,” says Bolton. As a planetary scientist, he studies planets other than Earth. Bolton reported the news on Jupiter’s clouds October 19 at a meeting, here, of the American Astronomical Society’s Division for Planetary Sciences.

The deep cloud cover “came as a surprise to many scientists,” Bolton notes. Until now, researchers weren’t sure if the planet’s colorful stripes were just blemishes on top of some thin band of clouds. In fact, those bands reach at least 350 to 400 kilometers beneath the cloud tops. That’s some 215 to 250 miles down.

Juno arrived at Jupiter on July 4. It made its first up-close investigation of the planet on August 27. The spacecraft came within 5,000 kilometers (3,100 miles) of the cloud tops. The orbiting probe recorded the intensity of radio waves coming from the planet. Different frequencies come from different depths. Low frequencies originate from deep in the atmosphere. High frequencies come from higher up.

“Deep down, Jupiter is similar — but also very different — than what we see on the surface,” said Bolton. Some bands broaden. Others vanish. “We can’t tell what all of it means yet,” he says. “But it’s telling us hints about the deep dynamics and chemistry of Jupiter’s atmosphere.”