Just as Earth’s magnetic field traps energetic charged particles to form Earth’s magnetosphere, the magnetic fields of the giant planets also trap energetic particles to form magnetospheres of their own. Earth’s magnetosphere is tiny compared to the vast clouds of plasma held together by the much more powerful magnetic fields of the giant planets. By far the most colossal of these is Jupiter’s magnetosphere. Its radius is as much as 100 times that of the planet itself, or roughly 10 times the radius of the Sun. Although the magnetospheres of the other giant planets are much smaller, even the relatively weak magnetic fields of Uranus and Neptune form magnetospheres that are comparable in size to the Sun.