2015 is International Year of Light (IYL2015) which ties in well with this observing session as, late in the XVII Century, the Galilean Moons were vital to the first serious experimental determination of the speed of light. So, this event is perfectly on time!
On 2 April 2015, starting at 18:45 UT, you will see live Callisto's shadow gradually move over Ganymede, the largest moon in our Solar System.
To watch this event is easy, simply head to the Virtual Telescope's WebTV
While watching this program why not take part in a bit of citizen science? By using the times of eclipses of the moons of Jupiter, we can all work together to do a large scale measurement of the speed of light, to help celebrate the International Year of Light. If you are interested in getting involved check out Measuring the Speed of Light with Roemer Delay. You can also do this yourself at other times over the year (March-July), with even a very simple telescope.
Translate Universal Time (UT) into your own timezone.
Share your experience with the world on Facebook or the Flickr group and Tweet using #GAM2015 (@gam_awb).
