How much of Jupiter's moon Europa is made of water? A lot,
actually. Based on the Galileo probe data acquired during its of
the Jovian system from 1995 to 2003, Europa posses a deep,
global ocean of liquid water beneath a layer of surface ice. The
subsurface ocean plus ice layer could range from 80 to 170
kilometers in average depth. Adopting an estimate of 100
kilometers depth, if all the water on Europa were gathered into
a ball it would have a radius of 877 kilometers. To scale, this
intriguing illustration compares that hypothetical ball of all
the water on Europa to the size itself (left) - and similarly to
all the water on planet Earth. With a volume 2-3 times the
volume of water in Earth's oceans, the global ocean on Europa
holds out a in the search for extraterrestrial life in our solar
system.