Juno clarified the true size of the giant, and now it is clear how much Jupiter has "worsened."

NASA’s Juno Refines Jupiter’s Size

The Juno mission has lasted almost a year, and thanks to this extended duration scientists were able to recalculate the dimensions of the largest planet in the Solar System. A new study published very recently contains more precise data on Jupiter’s diameters.

The difference is only 8–24 kilometers, but it confirms that Jupiter is slightly more flattened at the poles than previously thought. The ellipticity now stands at 7 %—almost twice that of Earth (0.33 %).

How were the new figures obtained?
Juno orbited Jupiter repeatedly while maintaining constant communication with a ground station. Variations over time in the radio signal’s travel time along the orbit allowed for a more accurate determination of the planet’s atmospheric and core boundaries. Reducing measurement errors by several times compared to earlier missions yielded a more reliable result.

Why is this important?
- Interior modeling – Accurate dimensions refine mass distribution, density, and pressure calculations within Jupiter.
- Atmospheric dynamics – Knowing the true size improves simulations of vortices, cyclones, and light interactions.
- Solar System evolution – Jupiter, which contains nearly 2 % of the system’s total mass, strongly influences other planets’ orbits and the transfer of volatiles (including water) to Earth.

Thus, even a seemingly minor adjustment in diameters helps eliminate old discrepancies in models derived from early probes. The new parameters for Jupiter will require revisions to gas‑giant theories and enhance the interpretation of future planetary data.