The scientists determined the planet has a radius of 71,484 kilometers (44,418 miles). Earlier data measured it at 71,492 kilometers (44,423 miles). The fifth planet from the sun, Jupiter is large enough to hold more than 1,300 Earths.<\/p>\n
\u201cWe have now, for the first time, an accurate measurement of the size of Jupiter,\u201d said Prof. Yohai Kaspi of Weizmann\u2019s Earth and Planetary Sciences Department, speaking to The Times of Israel. \u201cIt\u2019s a big deal in the sense that we never really knew the radius of this planet. We always had estimates. And now we have something more accurate, which has helped us solve a lot of things that were mysterious to us.\u201d<\/p>\n
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\t\t\t\tBy signing up, you agree to the terms<\/a><\/p>\n \t Jupiter: mostly gases with 95 moons<\/p>\n Jupiter contains mostly hydrogen and helium. The massive giant was \u201clikely the first planet to form in the solar system,\u201d Kaspi said.<\/p>\n \u201cWe know that because it\u2019s the biggest,\u201d he said. \u201cThere\u2019s no way that a small planet would form before such a big planet.\u201d<\/p>\n Kaspi said that the study of Jupiter\u2019s interior structure and its density provides scientists with evidence for how that formation took place.<\/p>\n \u201cWe had the sun, we had an explosion, then we had Jupiter, then Saturn, and then the rest of the planets,\u201d Kaspi said.<\/p>\n Scientists are still unclear if the planet has a central core of solid material. Circling it are 95 moons, rings, and asteroids.<\/p>\n The giant planet also has the shortest day in the Solar System. It takes Earth 24 hours to spin around. Jupiter\u2019s rotation lasts less than 10 hours.<\/p>\n \t Until now, estimates of Jupiter\u2019s shape were derived from six measurements that researchers made using NASA\u2019s Voyager and Pioneer missions 50 years ago. These missions sent radio beams from the spacecraft to Earth, providing a foundation of knowledge about Jupiter.<\/p>\n Then, NASA launched Juno<\/a> in 2011. After more than 2.8 billion kilometers (1.74 billion miles) and almost five years, it reached Jupiter and began orbiting the giant and sending back streams of raw data.<\/p>\n The spacecraft is the first to probe beneath Jupiter\u2019s dense, forbidding clouds. According to NASA, Juno is \u201clooking to answer questions about the origin and evolution of Jupiter, our solar system, and giant planets across the cosmos.\u201d<\/p>\n In 2021, NASA extended Juno\u2019s mission so the spacecraft could keep studying Jupiter and its moons more closely. Its new, expanded path placed the spacecraft in an orbit that allowed it to pass behind Jupiter from Earth\u2019s point of view, something its earlier orbit never did.<\/p>\n \t When the spacecraft passed behind the planet, its radio communication signal was blocked and bent by Jupiter\u2019s atmosphere.<\/p>\n Maria Smirnova, a PhD student in Kaspi\u2019s group at Weizmann, developed a special technique to process Juno\u2019s new data via the radio beam sent to Earth.<\/p>\n \u201cWhen the radio beam goes through the atmosphere of the planet, it bends a little bit,\u201d Kaspi described. \u201cWe measure this bending. The more it bends, the denser the atmosphere is.\u201d<\/p>\n Since the scientists \u201cknow exactly where Jupiter is, and we know where Earth is, and we know where the spacecraft is, then we can say what the density is at a certain distance from the center of the planet, and by that, we can set up the radius and the shape of the planet,\u201d Kaspi said.<\/p>\n \t Jovian winds and storms<\/p>\n Kaspi noted that NASA\u2019s earlier measurements also didn\u2019t account for Jupiter\u2019s powerful winds, some reaching 539 kilometers per hour (335 miles per hour).<\/p>\n Moreover, it is difficult to see what\u2019s happening beneath the planet\u2019s clouds.<\/p>\n \u201cThe radio data give us a window into the depth of Jupiter\u2019s zonal winds and powerful hurricanes,\u201d he said.<\/p>\n Kaspi\u2019s previous work on Jupiter\u2019s polar cyclones, with Dr. Nimrod Gavriel, a graduate of his group, provided critical insights to NASA for Juno\u2019s extended mission. The research was published<\/a> in the peer-reviewed journal PNAS.<\/p>\n Further understanding of Jupiter\u2019s winds will enable scientists to explain the relation between the planet\u2019s atmosphere and its deep interior.<\/p>\n \u201cWe\u2019re studying the winds, the storms, the magnetic field, and various aspects of the planet,\u201d he said. \u201cBy studying what\u2019s happening inside Jupiter, we get closer to understanding how the solar system, and planets like ours, came to be.\u201d<\/p>\n \u201cWhen you look at the sky at night, you see Jupiter, which is the biggest planet, and the brightest star,\u201d Kaspi said. \u201cUntil now, we knew roughly the size of that planet, and now we know exactly.\u201d<\/p>\n
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\n\t\tFrom left to right, Dr. Gidi Yoffe, Zohar Tal, Prof. Yohai Kaspi, Dr. Or Hadas, Dr. Maria Smirnova, Maayan Ziv, Dr. Eli Galanti, Rachel Navon, and Wuqiushi Yao of Weizmann Institute of Science\u2019s Earth and Planetary Sciences Department. (Courtesy\/Weizmann Institute of Science)<\/p>\n![\"\"](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2026\/02\/AP18193702376007.jpg\")
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\n\t\tThis April 3, 2017, image made available by NASA shows the planet Jupiter. (NASA, ESA, and A. Simon (GSFC) via AP, File)<\/p>\n![\"\"](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2026\/02\/jupiter1.jpg\")
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\n\t\tJupiter\u2019s south pole as seen by NASA\u2019s Juno spacecraft at a close pass. (Courtesy\/ NASA)<\/p>\n![\"\"](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2026\/02\/Jupiters-Slimmer-Profile-en2.jpg\")
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\n\t\tJupiter\u2019s profile updates after Weizmann Institute of Science researchers found a \u2018slimmer, flatter\u2019 planet. (Courtesy\/Weizmann Institute of Science)<\/p>\n
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