When in opposition, the 4 bright Jovian satellites may cross the disc of its parent planet in an event called transit. The satellite (white dot) is usually followed by the shadow (black dot) it casts on Jupiter. In this photo, Io is already exiting, with its shadow still on the disc of the planet. Image taken with a Logitech 4000 web camera through prime focus imaging setup.

Night Sky in Focus
Astronomy and Amateur Radio
© Anthony Urbano (Manila, Philippines)