If you have a medium sized telescope, you might like to watch tonight as Io and it’s shadow crosses the face of Jupiter. Io is one of Jupiter’s four largest Moons, commonly referred to as the Galilean moons after their discoverer Galileo Galilei.
According to Astronomy 2011, Io’s shadow begins its transit of Jupiter’s disc at 7.21 pm AEST (8.21 pm Daylight Savings Time) and exit Jupiter’s disc at 9.31 pm AEST (10.31 pm Daylight Savings Time) tonight (Sunday 11 December 2011). The above screen shot produced using the highly recommended Sky Safari Plus Apple Ipad app shows just how small the shadow will be compared to Jupiter. Look near the center of Jupiter to locate the tiny black shadow.
Using my Dobsonian telescope (8 inch aperture) and a high power eyepiece, I can just make out Io’s shadow as a clear, tiny circular disc. However, I have never been able to locate Io. I am assuming this is because Io is so much fainter than Jupiter but it could be because I was looking in the wrong spot.
