We were invited by the scouts in our school to give them a stargazing workshop in Tai Po. Each group was provided with a small 70mm telescope to set up by themselves and was then asked to aim it at the moon and Jupiter. After passing this 'test', the scouts were awarded with the view in the 8-inch telescope. They were mesmerised by the beautiful 'waves' (wrinkle ridges) on the 'bay of rainbow' (Sinus Iridum), and were excited to see the egress of Io (the volcanic moon of Jupiter). The rotation of the Jovian system reminded us of Galileo who watched the same phenomenon 400 years ago and then changed history.