NASA's Juno mission finds Jupiter smaller, flatter than previously thought

Data from NASA's Juno mission show that Jupiter, the largest planet in the solar system, is slightly smaller and more "squashed" than previously believed, the U.S. space agency said on Wednesday.

By analyzing radio occultation data from 13 close flybys of Jupiter and incorporating the effects of zonal winds, mission scientists found that the gas giant is about 8 km narrower at the equator and about 24 kilometers flatter at the poles, according to the latest research published in Nature Astronomy.

Radio occultation is used to "see" through the dense, opaque clouds of Jupiter's atmosphere to understand its internal structure, said NASA. During an occultation experiment, Juno transmits radio signals to NASA's Deep Space Network on Earth.

"When Juno passed behind Jupiter from Earth's perspective, its radio signal traveled through the planet's atmosphere before reaching Earth," planetary scientist Eli Galanti of the Weizmann Institute of Science in Israel, the lead author of this study, told Reuters.

"Measuring how the signal changed due to Jupiter's atmospheric composition, density and temperature allowed us to probe the atmosphere and determine the planet's size and shape with high precision. Interestingly, this geometrical configuration did not occur during Juno's prime mission, so these experiments were not originally planned," Galanti said.

Jupiter's precise radius serves as a key calibration standard for modeling giant exoplanets in other star systems. A more accurate understanding of the planet's shape will help astronomers better interpret observations of distant planets as they pass in front of their host stars, the agency said.

(With input from agencies)