Turns Out Jupiter Isn't The Size And Shape We Thought, NASA Says

by Aaron Leong — Thursday, February 05, 2026, 10:03 AM EDT

We are now finding out that Jupiter is not be as big as once thought. New evidence from the Juno orbiter suggests that textbooks need to be revised as the giant is actually a little more squashed (by about 15 miles) at the poles and slightly slimmer (by roughly 5 miles) at the equator.

In a study published this week in Nature Astronomy, an international team of researchers using data from NASA’s Juno mission has redefined the physical dimensions of the gas giant. By analyzing 26 radio occultation measurements (made possible by Juno’s extended mission trajectory), it was found that Jupiter is approximately 8 kilometers (about 5 miles) narrower at its equator and 24 kilometers (about 15 miles) flatter at its poles than the consensus established by the Voyager and Pioneer missions in the late 1970s. While these discrepancies might seem trivial for a planet that spans over 140,000 kilometers, this effectively corrects a 50-year-old error.

juno weizmann — *Jupiter is slightly smaller than previously estimated (Credit: Weizmann Institute of Science)*

As mentioned, the revised measurements were achievable via radio occultation. As the Juno spacecraft passed behind Jupiter from Earth’s vantage point, its radio signals traveled through the planet's upper atmosphere, known as the ionosphere. The gases in the atmosphere caused these signals to bend and delay, allowing the team to calculate the planet's temperature, pressure, and density with 10 times more precision than before. Lead author Eli Galanti noted that shifting the radius by just these few kilometers allows the models of Jupiter’s mysterious interior to finally reconcile with both gravitational data and atmospheric measurements.

This increased oblateness is a direct result of Jupiter’s ferocious rotation speed and the complex dynamics of its internal winds. The planet is about 7% wider at its equator than it is from pole to pole, compared to, say, Earth’s relatively modest 0.33% bulge. These updated dimensions confirm that Jupiter's powerful zonal winds, which create its iconic stripes, are largely barotropic, meaning they remain consistent in their intensity even deep below the visible cloud tops.

It probably goes without saying that these findings have implications for the study of distant worlds: Jupiter has always served as the primary standard for astrophysicists modeling gas giants orbiting other stars. Therefore, a more accurate understanding of Jupiter’s size and shape means that when astronomers observe an exoplanet passing in front of its host star, they can more precisely interpret its mass, composition, and potential for habitability.