New measurements indicate that Jupiter is slightly smaller and more flattened than previously believed. According to a study, researchers using data from NASA’s Juno spacecraft have provided the most precise dimensions of the gas giant to date. The updated measurements at the 1-bar pressure level show a polar radius of 66,842 km and an equatorial radius of 71,488 km, which are roughly 12 km and 4 km smaller, respectively, than previous estimates based on the 1970s Pioneer and Voyager missions.
Radio Occultation Data Redefines Jupiter’s Size
According to a Nature Astronomy report, scientists used repeated radio occultation observations to track how radio signals bend while passing through Jupiter’s thick atmosphere, allowing more accurate mapping of temperature, density, and overall planetary shape.
Previous size estimates were based primarily on data collected during the Pioneer and Voyager missions in the late 1970s. At that time, scientists had only six radio occultation measurements to work with, which left a significant margin for uncertainty. Those early readings could not fully account for the planet’s complex atmospheric effects or the powerful zonal winds that whip around the gas giant.
These high-speed winds distort the atmosphere and influence the planet’s shape, a factor that modern researchers have now integrated using far more extensive data from the Juno mission.
Advanced Observations Refine Jupiter’s Radius
Improved orbital dynamics and improved data processing techniques enabled researchers to obtain more consistent, higher-quality observations. The equatorial radius is also seen to be slightly smaller than earlier calculations, with the poles more flattened.
Experts mentioned that these small adjustments are scientifically meaningful because precise dimensions help refine models of Jupiter’s deep interior. More precise models also help inform our comprehension of the other gas giants in far-off planetary systems.
