Astronomy has come a long way since the time when Galileo Galilei first discovered satellites in Jupiter’s orbit in the 17th century and ending with a consistent depiction of a rare phenomenon: the transit of three Galilean satellites in front of the gas giant.
Occurring once or twice a decade, the transit of the satellites Europe, Callisto and Io is a predictable event and we were lucky to see it with the Hubble Space Telescope. The transit occurred on January 23.
Jupiter has a total of four satellites: Ganymede is not visible in this image. This photo taken by the Hubble camera Wide Field Camera clearly shows the shadows from the satellites Europe, Callisto and Io.
