Lucky sky-watchers in Antarctica and southern Africa will get a treat this weekend when the moon’s disk glides across the face of the sun creating a magnificent partial solar eclipse just after sunrise on Sunday, September 13.

The Earth crosses between the moon and the sun every month, but the three celestial bodies don’t always line up. A total solar eclipse occurs only when all three fall into perfect alignment such that the moon casts its dark central shadow, called the umbra, onto a very narrow strip of Earth’s surface.

During a more-common partial eclipse, such as the one this weekend, the Earth passes into only the moon's outer, much wider shadow cone, known as the penumbra, which creates a less