This is an drawing of the Galileo probe exploring Jupiter's environment.
Click on image for full size
Image from: The Jet Propulsion Laboratory
The Atmosphere of Icy Moons
The icy moons have no atmosphere. The reason they have no atmosphere is because they do not have enough gravity. The smaller the body is the lower its gravity, so moons have much less gravity than a planet has. Because there is little gravity, an icy moon cannot hold onto an atmosphere for very long.
An atmosphere can come from inside a moon. Some icy moons may have active surfaces, such as Europa, where the surface may "crack" and release molecules for an atmosphere from inside the moon.
However they get there, molecules may float around a moon for a while, but whatever "atmosphere" may be created disappears as soon as it is made.
Shop Windows to the Universe Science Store!
Our online store
on science education, classroom activities in The Earth Scientist
specimens, and educational games
You might also be interested in:
Many exciting discoveries were made about Europa during the Galileo mission. The surface of Europa is unusual, even for an icy moon. It appears that the surface is pretty new, rather than being ancient....more
Amalthea was discovered by E Barnard in 1872. Of the 17 moons it is the 3rd closest to Jupiter. Amalthea is about the size of a county or small state. Amalthea is named after the goat in Greek mythology...more
Callisto was first discovered by Galileo in 1610. It is the 2nd largest moon in the solar system, and is larger than the Earth's moon. It is about as big as the distance across the United States. Callisto...more
Measurements by the Galileo spacecraft have been shown that Callisto is the same inside from the center to the surface. This means that Callisto does not have a core at the center. This means that, unlike...more
Many different types of surface are shown in this picture. In the front is a huge crater, which goes for a long way over the surface. This crater could be compared to that of Mimas. They both show that...more
The surface of Callisto is deeply marked with craters. Craters are the little white marks in the picture. It looks like it might be the most heavily cratered body in the whole solar system. And some of...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 ( miles) from Jupiter. Europa's diameter is about half the distance...more