Jupiter is slightly smaller and more flattened at its poles than previously measured, according to new data from NASA’s Juno spacecraft. Scientists determined the gas giant is approximately 8 kilometers (5 miles) narrower at the equator and 24 kilometers (15 miles) flatter at the poles, refining earlier estimates of the planet’s dimensions.
The findings, published in the journal Nature Astronomy, stem from analysis of data collected during 13 of Juno’s close flybys of Jupiter. The research team employed a technique called radio occultation, which allows them to effectively “notice” through the planet’s dense, turbulent atmosphere.
Radio occultation works by analyzing the way Juno’s radio signals bend and warp as they pass through Jupiter’s upper atmosphere before reaching NASA’s Deep Space Network on Earth. Subtle delays in signal arrival times, caused by these atmospheric effects, reveal information about temperature, pressure, and electron density at various depths.
Juno entered orbit around Jupiter on July 4, 2016, becoming the first spacecraft to peer beneath the planet’s cloud cover and investigate its composition, gravity, and magnetic fields. The spacecraft is operated by NASA’s Jet Propulsion Laboratory (JPL) and was built by Lockheed Martin Space. As of February 2026, Juno has completed 76 planned orbits and continues to operate in an extended mission phase.
Although the new measurements provide a more precise understanding of Jupiter’s shape, NASA officials say the study has broader implications for the study of exoplanets – planets orbiting stars beyond our solar system. Astronomers frequently use the transit method to detect and characterize exoplanets, measuring dips in starlight as a planet passes in front of its host star.
The data from Jupiter can serve as an analogue for interpreting transit data from exoplanets, helping scientists to more accurately determine the size, composition, and even atmospheric properties of these distant worlds. The bending of radio signals through Jupiter’s atmosphere is similar to the way starlight bends as it passes through an exoplanet’s atmosphere during a transit, providing a valuable comparison point.
Juno’s extended mission, scheduled to continue through September 2025, will focus on exploring Jupiter’s full system, including its rings and moons, with planned rendezvous with Europa and Io. The spacecraft launched on August 5, 2011, from Cape Canaveral, Florida, aboard an Atlas V 551 rocket.
