August 8, 2022
Tonight at 8:30 pm, two of Jupiter’s largest moons, Ganymede and Io, will pass between the planet and the Sun, casting shadows and creating a double transit. The event will begin around 8:30 pm and end at 10 pm; however, Jupiter will not have risen yet. Another double transit of Ganymede and Io will occur on August 15th at 10:59 pm and last until approximately 12:40 am. Jupiter will be visible in the eastern sky at this time, and the transit will be visible with a telescope.
To calculate the positions of Jupiter’s 4 largest satellites for any given date, visit: https://skyandtelescope.org/wp-content/plugins/observing-tools/jupiter_moons/jupiter.html
The eastern sky as it will appear at 11 pm on August 15, 2022. The Moon, Jupiter, and Saturn will be visible in the east-southeastern sky. A double transit of Ganymede and Io will be visible from 10:59 pm to 12:40 am. It will be possible to see the shadows of both moons crossing the upper atmosphere of Jupiter, as shown in the bottom right image. Star map created using Stellarium