During its 40th close pass above Jupiter’s cloud tops, NASA’s Juno orbiter captured a spectacular image of Ganymede’s shadow from a distance of about 71,000 kilometres (44,000 miles), 15 times closer than the moon’s 1.1 million kilometre (666,000 mile) orbit. The elongated shadow marks a total eclipse of the Sun, a phenomenon that occurs much more frequently on Jupiter than on Earth thanks to its four Galilean moons. Such “shadow transits” across Jupiter are frequent targets for amateur astronomers, but the distance between the giant planet and Earth reduce those shadows to small black dots. From Juno’s perspective, the view is much more impressive. This enhanced colour image was processed from JunoCam data by citizen-scientist Thomas Thomopoulos.
Astronomers from Boston University have discovered that Jupiter’s Great Red Spot (GRS) may provide the mysterious source of energy required to heat the planet’s upper atmosphere to the unusually high values observed. Heating in Jupiter’s atmosphere 500 miles above the GRS is thought to be caused by gravity waves and acoustic waves creating turbulent atmospheric flows.