It seems only yesterday that the magnificent Hubble Space Telescope (HST) launched. But in reality, it was April 24, 1990. Since then, it’s been consistently the most visible science story in the mass media – there’s something about gorgeous astrophotography that engages the public. But behind the beautiful photos, there are important discoveries the Hubble has enabled. Learning about dark energy and the rate of the expansion of the universe, the first direct image of a planet outside our solar system, and the Hubble Deep Field Shot (see below), the most magnified picture of a spot of the sky ever taken with optical light -- all are among HST’s long list of accomplishments. The Deep Field Shot (NASA). Click to enlarge. This week, we heard the latest staggering revelation – the best evidence yet for an underground saltwater ocean on Ganymede , Jupiter’s largest moon. It may have more water than all of Earth’s oceans. In a fa