When you look at Jupiter through a telescope, you usually see four moons lined up with the planet. From time to time, a moon may pass in front of Jupiter’s disc in an event called a transit. A transit is a rare event since it occurs only when at least one moon lines up with Earth and Jupiter. On August 15, 2021, however, three of Jupiter’s four largest moons—Europa, Ganymede, and Callisto—passed in front of Jupiter, a very rare event which I have observed and captured using a small telescope.
Night Sky in Focus | Astronomy and Amateur Radio © Anthony Urbano | Manila, Philippines