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Juno caught the key evidence in radio signals that bent as the spacecraft passed behind Jupiter, from Earth\u2019s view.<\/p>\n
By tracing that bending through the planet\u2019s atmosphere, Dr. Eli Galanti at Weizmann Institute of Science<\/a> tied each signal to a sharper outline of Jupiter\u2019s body.<\/p>\n Older spacecraft records had left the planet\u2019s dimensions slightly inflated, partly because they did not account for its powerful winds.<\/p>\n The updated outline now sets the reference points scientists need before they connect Jupiter\u2019s atmosphere to what lies far below.<\/p>\n Why Jupiter\u2019s shape matters<\/p>\n A gas giant<\/a> \u2013 a planet made mostly of hydrogen and helium \u2013 has no solid surface, so scientists choose a pressure level to mark its size.<\/p>\n Near the atmospheric pressure level that scientists use as Jupiter\u2019s official boundary, the revised measurements slightly shrink the planet\u2019s long-accepted dimensions.<\/p>\n That narrower profile changes the baseline used to interpret Jupiter\u2019s gravity, temperatures, and deep internal structure.<\/p>\n Even small corrections matter at Jupiter\u2019s scale, because tiny changes in radius ripple through nearly every model used to explain the planet.<\/p>\n Old numbers lingered<\/p>\n For decades, Jupiter\u2019s standard dimensions rested on six radio occultation<\/a> measurements \u2013 signal-bending tests \u2013 from NASA\u2019s Voyager and Pioneer spacecraft.<\/p>\n Earlier spacecraft gave planetary scientists a foundation, but their data came from only a few paths through Jupiter\u2019s atmosphere.<\/p>\n \u201cThose missions provided a foundation, but now we got the rare opportunity to spearhead the analysis of as many as 26 new measurements made by NASA\u2019s Juno spacecraft,\u201d said Galanti.<\/p>\n The new measurements also resolved mismatches that had persisted between spacecraft observations and models of Jupiter\u2019s atmosphere and interior.<\/p>\n Winds changed Jupiter\u2019s shape<\/p>\n Fast east-west winds also reshape Jupiter, because moving air changes the forces acting on the planet\u2019s outer layers.<\/p>\n Earlier estimates treated Jupiter mostly as a rotating body without adding the extra shape changes that are driven by those winds.<\/p>\n After the team included zonal winds \u2013 broad east-west streams in a planet\u2019s atmosphere \u2013 the old mismatch eased.<\/p>\n That result means Jupiter\u2019s upper winds stay fairly similar with height, rather than changing sharply between the levels that Juno sampled.<\/p>\n Near the level used for planetary maps<\/a>, the equatorial radius fell by 2.5 miles (4 kilometers) in the reference value.<\/p>\n Pole to pole, the update removed about 15 miles (24 kilometers) from the diameter once used in standard references.<\/p>\n Mean radius changed by about 5 miles (8 kilometers), which matters when researchers compare Jupiter with giant planets around other stars.<\/p>\n Small corrections gain power because gravity, temperature, pressure, and wind all connect through the same planetary shape.<\/p>\n Inside the giant<\/p>\n Computer models of Jupiter\u2019s interior depend on the chosen radius, because a smaller outer boundary makes Jupiter slightly denser in calculations.<\/p>\n That denser setup lets models allow a cooler atmosphere and more heavy material mixed into the outer layers.<\/p>\n The change helps reconcile gravity readings from Juno with temperature clues from NASA\u2019s Galileo probe \u2013 a capsule that entered Jupiter\u2019s atmosphere \u2013 and Voyager observations.<\/p>\n Storms add depth<\/p>\n Jupiter\u2019s polar storms strengthen the same lesson, because their motion reveals how deeply weather can reach.<\/p>\n A related study<\/a> of polar cyclones \u2013 huge spinning storms near a planet\u2019s poles \u2013 used Juno observations to link westward drift with storm depth.<\/p>\n Slow drift suggests vertical structure, since deeper or shallower storms move differently under Jupiter\u2019s rotation.<\/p>\n That boundary helps researchers avoid mistaking weather-driven shape changes for signs of deep structure when they build interior models.<\/p>\n Another spacecraft will test these ideas as Jupiter research moves from shape to deeper atmospheric layers.<\/p>\n The Juice mission<\/a> \u2013 Europe\u2019s Jupiter Icy Moons Explorer \u2013 was launched in 2023 to study Jupiter and three moons thought to hold buried oceans.<\/p>\n A Weizmann-designed instrument will look deeper into Jupiter\u2019s atmosphere by tracking very stable radio signals during future passes.<\/p>\n Broader coverage could expose whether the new reference shape holds at latitudes that Juno did not sample well or at deeper levels.<\/p>\n Limits still matter<\/p>\n Precision does not mean every part of Jupiter is now equally measured or equally well understood.<\/p>\n Juno\u2019s radio paths covered many low and middle latitudes, while high southern latitudes<\/a> and the equator remained less sampled.<\/p>\n No Juno radio measurement reached the 1-bar level, so researchers linked that reference depth to older data.<\/p>\n Those gaps make the new shape much stronger than before, but not final in every possible detail. Future missions will need to test the details.<\/p>\n Jupiter\u2019s shape redefined<\/p>\n A slimmer Jupiter now connects atmospheric winds, spacecraft signals, and interior models in one cleaner planetary reference.<\/p>\n Future radio and microwave measurements can refine that reference further, especially where Juno obtained only sparse coverage.<\/p>\n The study is published in Nature Astronomy<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"A new study has redefined gas giant Jupiter\u2019s dimensions. The study found that the planet is about 5…\n","protected":false},"author":2,"featured_media":419435,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[111,139,69,147,392],"class_list":["post-419434","post","type-post","status-publish","format-standard","has-post-thumbnail","category-space","tag-new-zealand","tag-newzealand","tag-nz","tag-science","tag-space"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/419434","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/comments?post=419434"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/419434\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media\/419435"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media?parent=419434"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/categories?post=419434"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/tags?post=419434"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"The](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2026\/05\/jupiter-shape_juno-mission_oval_Nature_1s-1.webp.webp\")
<\/a>The shape of Jupiter redefined by Juno. Right: 1-bar shapes (not to scale), showing the L81 shape based on the V1E occultation, neglecting winds3 (dashed black line); the full shape from this study (blue line); and the corresponding no-wind shape (dashed red line). Left: an image of Jupiter. Credit: image of Jupiter, NASA \/ JPL-Caltech \/ Nature Astronomy. Click image to enlarge.A smaller reference<\/p>\n![\"Jupiter\u2019s](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2026\/05\/jupiter_south-pole_Juno-mission_NASA_1s.webp.webp\")
<\/a>Jupiter\u2019s south pole as seen by NASA\u2019s Juno spacecraft at a close pass. Photo courtesy of NASA. Click image to enlarge.Future measurements await<\/p>\n