I always love this time of year: the summer twilight is receding, it’s still quite mild in the evenings and the Globular clusters start to become visible again. I like to image these beautiful objects and there are many of them, well-placed in the sky at the moment.
The chart shows the view from Edinburgh at about 10:30pm (BST) as astronomical twilight ends on the 1st of September, looking South. Eight of the brighter Globulars are marked on the chart but there are other fainter ones too. Locate them using your favourite planetarium program.
The brighter ones, such as the Great Gloublar M13 in Hercules and M15 in Pegasus, are relatively easy to observe, even with binoculars. But it takes a telescope to start to resolve the individual stars and imaging to really bring out the details.
Globular clusters are very densely packed collections of stars, usually spherical in shape, containing thousands to millions of relatively old stars, distributed in a halo surrounding our galaxy. There are about 150 known Globulars in our galaxy. They probably formed before the rest of the galaxy stabilised into a disc and so contain some of the oldest stars in our galaxy.
If you manage to image or observe any Globular clusters this season, why not post your images and observations to our Flickr group, Facebook page or Twitter feed.
Mark Phillips
Chart: Dominic Ford in-the-sky.org
M13 image: Mark Phillips