They’ve arrived! Images from NASA’s Juno spacecraft P7 pass have landed on Earth (a few days early no less) showing Jupiter’s Great Red Spot from the closest distance that it’s ever been imaged before. Captured on the night of July 10 (early July 11 morning UTC) the closest Junocam images were taken from a distance of only about 5,600 miles from the top of the storm’s clouds—that’s less than an Earth diameter away from a hundreds-year-old hurricane an Earth and a half wide!
Today, July 10 (July 11 UTC) NASA’s Juno spacecraft will make its first targeted flyover of Jupiter’s famous Great Red Spot since its arrival in orbit on July 4, 2016, getting our best look yet at the giant anticyclonic storm that’s been churning on the giant planet since at least 1830 (and possibly even since before 1665.)
Previous spacecraft (Voyager, Galileo, Cassini, New Horizons) have imaged the Great Red Spot but none from as close a distance as Juno will tonight. During P7—Juno’s seventh “perijove,” or closest point to Jupiter in its 53-day-long orbital path—Juno will pass over the GRS at an altitude of only about 5,600 miles.
Perijove (the point at which an orbit comes closest to Jupiter’s center) will be on Monday, July 10, at 6:55 p.m. PDT (9:55 p.m. EDT). At the time of perijove, Juno will be about 2,200 miles (3,500 kilometers) above the planet’s cloud tops. Eleven minutes and 33 seconds later, Juno will have covered another 24,713 miles (39,771 kilometers) and will be directly above the coiling crimson cloud tops of Jupiter’s Great Red Spot. The spacecraft will pass about 5,600 miles (9,000 kilometers) above the [Great] Red Spot clouds.
Once the flyover data is transmitted and received on Earth sometime on Friday, July 14 we can expect amateur image processors (myself definitely included!) to feverishly get to work bringing out as many details as possible in the raw data. (You can find raw images from Junocam and processed versions from the public here.) This, as they say, is going to be good!
Source/read more from NASA here: NASA’s Juno Spacecraft to Fly Over Jupiter’s Great Red Spot July 10
It used to be said with confidence by even grade-school kids that the largest storm in the Solar System was Jupiter’s Great Red Spot, which has been churning for at least 350 years and could fit three Earths across it. And while it’s true that the GRS is a truly enormous hurricane by Earthly standards, these days it’s not as “great” as it used to be — over the past couple of decades the GRS has shrunk to only about a third of its former size.
“Recent Hubble Space Telescope observations confirm that the Great Red Spot (GRS) is now approximately 10,250 miles across, the smallest diameter we’ve ever measured,” said Amy Simon of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
That equals about 16,500 kilometers, or about one and one-third Earths across. Which is still very big, yes, but nothing compared to what it once was!