Scientists are reasonably certain that Jupiter’s moon Europa contains water in the form of massive oceans underneath its icy crust. This has made the moon especially interesting, as water generally means there's potential for life. Although we have no direct evidence of life existing in that icy ocean, some scientists are planning future expeditions to Europa to find out. Meanwhile, though, we can enjoy the Hubble telescope’s observations as huge geysers erupt from Europa and surge to over 100 miles above its surface.
Hubble originally observed Europa’s plumes of water late last year. Scientists looked over the telescope’s images and noticed areas that showed an aurora of ultraviolet light. They determined that this light was created by water molecules being broken apart by Jupiter’s magnetic field as they shot into the sky. Scientists believe that there are cracks on Europa’s icy layer that act as vents for the water vapor. This would be in line with previous observations on Enceladus.
The Hubble data also shows that the water jets seem to stop when Europa is closest to Jupiter. This is probably due to Jupiter’s gravity, which creates a tidal pull that closes the cracks when the moon is close to the planet, and opens them when it’s farther away. This provides further evidence of the oceans that exist underneath Europa’s surface.
This is an exciting discovery because it means we can now study the water vapors to determine the chemical composition of Europa without having to drill through its thick top layer. Who knows, maybe those jets of water also contain microbial life, and it’s only a matter of time before we find it.