Adrian Dening's Stars Over Somerset

Wednesday, 26 March 2025 22:41

Monday 31st March to Sunday 6th April 2025

Now we have moved forward into British Summer Time, all the times I quote on Stars Over Somerset will be local, so you can just look at your clock and not worry about converting anything.

Venture outside at 9pm on Tuesday 1st April and look towards the west to spot a 16%-lit waxing crescent Moon. Over the following couple of hours, the Moon will gradually occult (or cover-up) all the stars of the Pleiades open cluster. The Pleiades is also known as the "Seven Sisters" because there are seven particularly bright stars within the cluster that are easy to spot with the naked eye.

The Pleiades is about 440 light years away from us, which converts to a little over 4000 trillion Km. The Moon is only 360,000Km away at this point in its orbit around us, so it appears to move in front of the cluster and blocks the Seven Sisters from your view.

Open clusters of stars can vary from tens to thousands of stars that are all about the same age, as they were born in the same molecular cloud - I mentioned one of these "stellar nurseries" last week - the Great Orion Nebula. You can also come across globular clusters that contain thousands to millions of stars, all kept together by their mutual gravity - a bit like a mini galaxy. An excellent example is the Great Globular Cluster in Hercules, also known as Messier 13, that is around 22,000 light years away.

If you've brought your telescope out to see the occultation, around 11pm point it towards the north east instead. Find the constellation of Lyra with the bright star Vega and Messier 13 will be a little above and to the right of Vega.