Shallow Solar eclipse

Yesterday, 13 July, ominously a Friday, a very shallow eclipse of the Sun was visible from Melbourne. It was not a rare total eclipse so it was of little scientific interest. Even some amateur astronomers ignore with disdain an eclipse with only such a tiny bite taken out of the Sun's disk. Yet to me it was of great interest as it was to be proof of the astronomical calculations predicting the eclipse. In the 2018 Australasian Sky Guide on the page for the July sky I put in the prediction for a 9.5% eclipse for Hobart, 2.3 % for Melbourne and 0.1% for Adelaide. Was the prediction going to come true?

The sky was cloudy but there were gaps. Optimistically I set up the small lens telescope and placed the Sun filter in front of the objective lens. And sure enough at the predicted time I could see the disc of the Sun with a tiny missing notch that hardly grew over the next few minutes until the maximum of the eclipse. The prediction was validated!

The two pictures were taken by hand-holding a small digital camera to the telescope eye piece, a technique called parfocal photography. The first image (above) was at the eclipse maximum, while the second (below), was taken using a shorter focal length eye piece to give a larger image, five minutes later. As can be seen the Sun was featureless without a solitary sunspot.

The eclipse that everyone is waiting for is the total eclipse of the Moon in two week’s time on 28 July from 4:24am. That will be much more spectacular and it will be worth getting up early for it even on a Saturday morning.

Nick Lomb is a Life Member of Sydney City Skywatchers. He is author of the Australasian Sky Guide published annually by MAAS, an astronomer and was the curator of astronomy, horology, meteorology and Sydney Observatory for the Museum of Applied Arts and Sciences.