A drawing of space near Jupiter, showing a portion of the radiation belts (in red), the Io torus (green) and the Europa torus (blue). The blue and green belts come from the atmospheres of the moons Europa and Io. The picture comes from measurements taken by the Cassini spacecraft.
The Atmosphere of Europa
The Galileo mission
discovered something amazing! Europa has its own atmosphere, although it is very, very thin. This atmosphere is created when fast moving molecules in Jupiter's magnetosphere
hit the surface of Europa and knock out a water molecule. These molecules may float around Europa for awhile, but because of Europa's weak gravity, the "atmosphere" rapidly drifts away.
This picture shows what sometimes happens inside the magnetosphere of Jupiter (shape indicated by the white lines) when molecules from one of its moons float into it. They create a 'torus' (the blue and green belts that are shown in this picture).
Because Europa has an atmosphere with molecules that can escape, there is a donut-shaped belt of material inside Jupiter's magnetosphere that is called the "Europa torus". Jupiter's moon Io also has a torus
. Even though Ganymede
also have thin atmospheres, they do not seem to produce torii in Jupiter's inner magnetosphere. This probably has something to do with the shape of Jupiter's magnetosphere.
You might also be interested in:
The Galileo spacecraft was launched on October 19, 1989. Galileo had two parts: an orbiter and a descent probe that parachuted into Jupiter's atmosphere. Galileo's main mission was to explore Jupiter and...more
Jupiter's magnetosphere is very special. It is the biggest thing in the entire solar system. Not only is it big enough to hold all of Jupiter's moons, but the sun itself could fit inside. It goes all...more
A satellite which has an atmosphere, such as Jupiter's moon Io, and which also is inside a magnetosphere (unlike the Earth's moon), will leave a cloud of particles behind as it orbits the planet. This...more
Callisto was first discovered by Galileo in 1610, making it one of the Galilean Satellites. Of the 60 moons it is the 8th closest to Jupiter, with a standoff distance of 1,070,000 km. It is the 2nd largest...more
Europa was first discovered by Galileo in 1610, making it one of the Galilean Satellites. It is Jupiter's 4th largest moon, 670,900 km from Jupiter. With a diameter that is about half the distance across...more
The Galileo spacecraft has finally reached the end of its road. Galileo has been orbiting Jupiter since 1995. On September 21, 2003, Galileo will dive into Jupiter's atmosphere and burn up. This crash...more
Amalthea was discovered by E Barnard in 1872. Of the 17 moons it is the 3rd closest to Jupiter, with a standoff distance of 181,300 km. Amalthea is about the size of a county or small state, and is just...more