Jupiter gets a makeover: NASA’s Juno mission reveals Jupiter is smaller, flatter than scientists thought
Jupiter's radius is now estimated to be about 5 miles smaller than previously thought, while the distance from pole to pole is about 15 miles less.
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Jupiter may be the largest planet in the solar system, but new research shows it’s not quite as big as scientists once believed, resulting in a planetary makeover.
Using data from NASA’s Juno spacecraft, researchers have refined Jupiter’s size and shape, finding the gas giant is slightly smaller at the equator and more flattened at the poles than previous measurements suggested. The findings were published in Nature Astronomy on Monday and could lead to updates in planetary science models and textbooks.
Jupiter is slightly smaller than previously estimated about 5 miles less wide at the equator and about 15 miles flatter at the poles. (Image credit: Weizmann Institute of Science)
The breakthrough comes from Juno’s use of a technique called radio occultation, which measures how radio signals change as they pass through a planet’s atmosphere. During multiple flybys, Juno sent radio waves back to Earth while slipping behind Jupiter from our point of view. As the signals traveled through the planet’s dense atmosphere, they bent and slowed, revealing details about temperature, pressure and atmospheric structure.
Those observations allowed scientists to fine-tune Jupiter’s dimensions. The planet’s equatorial radius is now estimated to be about 5 miles smaller than previously thought, while the distance from pole to pole is about 15 miles less. The result confirms Jupiter is more noticeably squashed than earlier calculations indicated.
That flattening is caused by Jupiter’s incredibly fast rotation, the gas giant takes one full spin takes less than 10 hours. According to NASA, accurately defining the planet’s shape helps scientists better understand how its massive gravity field works, how energy moves through its atmosphere and what lies deep beneath its swirling cloud tops.
FILE - This undated image shows shows an artist's rendering of NASA's Juno spacecraft making a close pass over Jupiter. On Thursday, Feb. 23, 2017, NASA said its the spacecraft is stuck making long laps around the gas giant because of sticky valves. (NASA via AP)
The updated measurements also have implications beyond Jupiter. Because the planet is often used as a reference for studying gas giants and distant exoplanets, even small changes to its known dimensions can improve how scientists interpret observations of planets orbiting other stars.
Juno, which arrived at Jupiter in 2016, was designed to probe below the planet’s thick clouds. Since then, it has revealed new insights into Jupiter’s magnetic field, deep atmospheric jets and mysterious interior. Jupiter itself hasn’t changed, but our understanding of it has.
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