ON 14 April this year, the European Space Agency sent a new spacecraft off on its eight-year journey to Jupiter. The Jupiter Icy Moons Explorer (JUICE, illustrated above) will fly by three of Jupiter’s four biggest moons, Europa, Ganymede and Callisto, before going into orbit around Ganymede, the biggest moon in the solar system. This is an exciting mission because these icy moons, with their subsurface oceans, are some of the most promising places to look for life. And now that Jupiter is once again appearing in our night skies, we can see those icy moons ourselves.
The four…