Jupiter isn’t as huge as we thought it was
“Textbooks will need to be updated”: the solar system’s largest planet appears to be smaller and flatter than we knew
Voyager’s “Blue Movie” of Jupiter.
The solar system’s most giant planet is slightly less of a giant than scientists once thought. Jupiter, a world that is so huge that it could hold 1,000 Earths, is eight kilometers narrower in width at its equator and 24 kilometers flatter at its poles than had been previously estimated, according to a new study.
The new measurements overturn almost 50 years’ worth of consensus about the size and shape of the planet.
“Textbooks will need to be updated,” said Yohai Kaspi, a professor at the Weizmann Institute of Science in Rehovot, Israel, and senior author of the study, in a statement. “The size of Jupiter hasn’t changed, of course, but the way we measure it has.”
On supporting science journalism
If you’re enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
Previously, scientists relied on observations by the Voyager and Pioneer spacecraft, which were launched by NASA in the 1970s. But NASA’s Juno mission, which launched in 2011 and reached Jupiter in 2016, has proved to be a game changer: By orbiting over Jupiter’s poles for the first time, it allowed for clearer observations of Jupiter’s size.
The research means scientists have to adjust their models of Jupiter, a change that will have resounding implications for both studying the planet’s features, such its volatile atmosphere, and understanding how gas giants like Jupiter formed in the first place.
“Jupiter was likely the first planet to form in the solar system,” Kaspi said in the same statement, “and by studying what’s happening inside it, we get closer to understanding how the solar system, and planets like ours, came to be.”
Editor’s Note (2/2/26): This article was edited after posting to include comments from Jonathan McDowell and to correct the descriptions of his social media post and the number of active satellites that are orbiting Earth.
It’s Time to Stand Up for Science
If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.
I’ve been a Scientific American subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.
If you subscribe to Scientific American, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.
In return, you get essential news, captivating podcasts, brilliant infographics, can’t-miss newsletters, must-watch videos, challenging games, and the science world’s best writing and reporting. You can even gift someone a subscription.
There has never been a more important time for us to stand up and show why science matters. I hope you’ll support us in that mission.
source: https://www.scientificamerican.com/article/jupiter-isnt-as-huge-as-we-thought-it-was/
