Once every 53 days, Jupiter pulls Juno close. Locked in orbit since July 2016, the spacecraft has made five close flybys of the planet so far. More than 1,300 Earths could fit inside Jupiter, but Juno takes only two hours to zip from pole to pole. That mad, north-to-south trek is shown below in a sequence of 14 enhanced-color images taken May 19.
Each image’s width corresponds to the width of the field of view of JunoCam, Juno’s visible light camera. As the spacecraft zooms closer, to about 3,400 kilometers above the cloud tops, less total area of Jupiter can be seen, but more details emerge. Turbulent clouds, for example, signal massive tempests along the equator. New data from the mission reveal that near the equator, ammonia rises from unexpectedly deep in the Jovian atmosphere (SN Online: 5/25/17). Such upwelling might fuel storms like these, but it’s too early for scientists to tell. And what look like pinpricks of light across the entire south tropical zone are actually 50-kilometer-wide cloud towers. Found high in Jupiter’s atmosphere, these clouds are probably made of ice crystals.“It’s snowing on Jupiter, and we’re seeing how it works,” said Juno mission leader Scott Bolton of the Southwest Research Institute in San Antonio in a May 25 news conference. Or “it could be hail,” he added. Either way, it’s not snow or hail as we know it. The precipitation is probably mostly ammonia ice, but there may be water ice, too.
Juno doesn’t have eyes only for Jupiter. Sometimes the spacecraft stargazes, too. On its initial science flyby last August, Juno captured the first image of Jupiter’s main ring seen from the inside looking out. In the background of the newly released image, Betelgeuse, in the constellation Orion, peeks above the gauzy band, and the three stars of Orion’s belt glint from the bottom right. Taken with Juno’s star-tracking navigation camera, the shot reveals that “heaven looks the same to us from Jupiter,” said Heidi Becker, leader of Juno’s radiation monitoring team at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.
These rendezvous won’t go on forever, but they could last into 2019.