april: lunar occultation of saturn

This month, on the 16^th, Europe is treated to a fascinating spectacle, as the dark edge of the Moon slowly slides across the elongated disc of Saturn. Then, an hour or so later, the planet will reappear on the Moon's opposite limb. The phenomenon is called an occultation, and given good weather it should be an interesting sight even with the naked eye.

As the Moon's complex orbit shifts in the sky it periodically crosses many objects, including half a dozen first magnitude stars, any of the planets and many asteroids, producing occultations visible from some parts of the Earth. Generally occultations of stars and outer planets will occur in a series of monthly encounters for several successive months before the Moon's orbit passes into another region of the sky.

In September last year it was the turn of North America to get the best view of an occultation of Saturn - in this case as the planet slid behind the Moon's bright limb. The stunning view above is a composite of images recorded using the Mount Wilson Observatory's 60 inch reflector.

Image copyright © 2002 Ron Dantowitz and Marek Kozubal,
The Clay Center at Dexter and Southfield Schools.