The Juno probe was commissioned to study Leviathan: Jupiterthe heavyweight of the solar system, the king of the planets.
But a planet the size of Jupiter, roughly 318 times the mass of Earth, is not without its friends.
The gas giant has 79 known moons (and maybe more), one of them is bigger than Mercury. Juno explores the relationship between some of those moons and the host planet – and on occasion, sees them display photo-blasting images of the large Jupiter itself.
The latest one is so stunning, it almost looks like a work of art from science fiction. Jupiter looms large, and its classic bands of plume, vortex cloud and spot-like cyclones are clearly visible in the southern hemisphere in sunlight.
(NASA/JPL-Caltech/SwRI/MSSS/AndreaLuck)
To the right of the giant planet, two relatively small dots glide softly against the inky darkness. These are two of the four Jupiter Galilee moons – Its largest moon, discovered by Galileo Galilei.
The two depicted here are the smaller of the four: Io, with equatorial diameter 3643.2 km (2,264 mi); and Europa, which has an equatorial diameter 3121.6 km (1,940 miles).
(NASA/JPL-Caltech/SwRI/MSSS/AndreaLuck)
Each of these moons is a wonderful target for study in and of itself. Io is the most volcanically active body in the Solar System, with more than 400 active volcanoes permeating its surface. This is the result of the placed internal gravitational pressures the moonnot only by Jupiter, but by the other three Galilean moons
This volcanic activity results in Io’s atmosphere becoming rich in sulfur dioxide, which is spewed out by volcanoes. This atmosphere is constantly leaking, forming a ring of plasma around Jupiter itself, which is directed along magnetic field lines to rain down on Jupiter’s poles, generating permanent auroras.
The continuous flow of sulfur has also enveloped Io itself in various sulfur compounds, giving the moon its mostly yellow colour.
True color photo of Io. (NASA/JPL/University of Arizona)
Europa, meanwhile, is the target of an interest in the search for extraterrestrial life. Beneath its icy, pale shell, a liquid inner ocean lurks. Although the Moon is far from the Sun, it may be heated internally by gravitational stress.
If this is the case, there may be hydrothermal vents on the global sea floor. Here on Earth, vents like these are havens for food webs that depend not on photosynthesis, but on chemosynthesis to survive: harnessing chemical reactions for food.
This led astrobiologists to believe that, of all the worlds in the Solar System, icy moons like Europa and Saturn’s Enceladus might be the most likely places to find extraterrestrial life.
Juno will be making flights close to these two very different worlds.
Europa, which is also the target of a custom mission Scheduled to be launched in 2024, the probe will visit it in September this year. It will be the closest probe to the moon in decades. In the meantime, Io’s flight launch is scheduled for late 2023 and early 2024.
You can download the full size version of this image From the NASA website.