Occultation is not coming over to the 'dark side' or black magic! It's the passing of one body in front of another, so a solar eclipse can also be described as occultation of the sun by the moon.

Although there are about 3,000 stars visible to the naked eye, the moon is so bright that when it approaches a star it, the star becomes invisible to the unaided eye, especially when they approach the bright side of the moon. Occultations of bright stars and planets by the moon are more common that eclipses, but still not as common as you might expect as the moon only covers a very narrow path through the sky. Sometimes a series of occultations can occur, hovever, such as the moon making multiple passes in front of Saturn a few years ago.

With a camera it's possible to capture the moments before the moon occults an object, although it is usually necessary to do some processing to the image if the object is a relatively dim one. The picture below shows delta Gemini - the star on the knee of the left had twin - a few minutes before it was occulted on 8 September 2015. The total length of the event depends on how close to the centre line of the moon the occulted object is, in this case it was very near and the event lasted over an hour before the star would reappear. Something I would like to achieve is having a telescope pointed on the dark edge of the moon ready to see the star reappear.

The moon, soon to occult the star Delta Gemini

The moon, soon to occult the star Delta Gemini

Category: Astrophotography