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Utilizing high-precision radio-occultation measurements from NASA’s Juno objective and integrating the impacts of zonal winds, planetary researchers obtained Jupiter’s shape with an order-of-magnitude decrease in unpredictability, discovering polar, equatorial and imply radii smaller sized than previous price quotes made with NASA’s Pioneer and Voyager objectives.
This visible-light picture of Jupiter was developed from information recorded on January 11, 2017 utilizing Hubble’s Wide Field Camera 3. Near the top, a long brown function called a’brown barge’extends 72,000 km (almost 45,000 miles) in the east-west instructions. The Great Red Spot stands out plainly in the lower left, while the smaller sized function nicknamed Red Spot Jr. (understood to Jovian researchers as Oval Bachelor’s degree) appears to its lower. Image credit: NASA/ ESA/ NOIRLab/ NSF/ AURA/ Wong et al/ de Pater et al/ M. Zamani.
“Jupiter, the biggest world in the Solar System, is roughly an oblate spheroid (ellipsoid of transformation), indicating it is somewhat flattened at the poles and bulging at the equator owing to its quick 9 h 55 minutes 29 s rotation duration,” stated Dr. Eli Galanti from the Weizmann Institute of Science and coworkers.
“This shape arises from the balance in between gravitational forces pulling inwards in the radial instructions and centrifugal forces pressing outwards from the rotation axis, resulting, when it comes to Jupiter, in the equatorial radius having to do with 7% bigger than its polar radius.”
“For a body with consistent density, the shape is a precise ellipsoid. Jupiter’s interior density profile differs significantly from the cloud level at around 1 bar, where the density is less than 1 kg/m3to the deep levels, where density reaches countless kg/m3“
“This results in variations in the shape of the world from an ellipsoid on the order of 10s of kilometers, which are revealed as latitudinal variations in the gravity field.”
“Additional variations in Jupiter’s shape originated from the strong zonal winds observed at the cloud level.”
“These customize the centrifugal forces to develop variations on the order of 10 km, mainly at low latitudes.”
Formerly, Jupiter’s physical measurements were based upon information from 6 radio occultation experiments carried out by NASA’s Pioneer and Voyager objectives in the 1970s.
In a brand-new research study, the authors examined the radio occultation information gotten by Juno throughout 13 flybys of Jupiter, and integrated the results of zonal winds.
“Radio occultation is utilized to ‘see’ through the thick, nontransparent clouds of Jupiter’s environment to comprehend its internal structure,” they discussed.
“During an occultation experiment, Juno beams radio signals back to NASA’s Deep Space Network in the world.”
“As these signals travel through the charged upper layer of Jupiter’s environment, called the ionosphere, gases bend and postpone the signals.”
“By determining the modification in frequency triggered by this flexing, we can determine the temperature level, pressure, and electron density of Jupiter’s environment at various depths.”
The group’s outcomes reveal that Jupiter has to do with 8 km narrower at the equator and 24 km flatter at the poles.
“Incorporating the impacts of zonal winds, we obtain Jupiter’s shape with an order-of-magnitude decrease in unpredictability,” the scientists stated.
“At the 1-bar pressure level, we discover a polar radius of 66,842 km, an equatorial radius of 71,488 km and a mean radius of 69,886 km, which are 12 km, 4 km and 8 km smaller sized than previous quotes, respectively.”
The findings were released today in the journal Nature Astronomy
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E. Galanti et alThe shapes and size of Jupiter. Nat Astronreleased online February 2, 2026; doi: 10.1038/ s41550-026-02777-x
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