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 km 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. As the signals pass through Jupiter's ionosphere, they are bent and delayed by atmospheric gases.

By measuring changes in the frequency of the signals, researchers can determine temperature, pressure and electron density at different depths of Jupiter's atmosphere, NASA added.

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.