Observers in the UK with a view low to the west about 1am BST on Saturday, 11 May 2019 (some 1½ hours before moonset for the centre of the British Isles) can see the 6-day-old waxing crescent Moon just 1½ degrees from the prominent open cluster Messier 44, otherwise known as Praesepe, or the Beehive Cluster. After the Moon has set in Western Europe its orbital motion brings it even closer to M44, actually occulting some of the cluster’s southernmost stars as seen from North America’s Eastern Seaboard just before local midnight on on 10 May. AN graphic by Ade Ashford.The Moon was new on 4 May, so the young lunar crescent soon makes its presence known at dusk, particularly in Northern Hemisphere skies where the ecliptic makes a steeper angle to the western horizon. If you own a pair of binoculars, you may wish to take a look at the Moon on the night of 10-11 May since it lies in the constellation of Cancer, the Crab, in the same field of view as the beautiful open star cluster known as Praesepe, the Beehive Cluster, or more prosaically as Messier 44.
For observers in Western Europe and the UK, the Moon’s orbital motion doesn’t bring it close to the Beehive Cluster until the calendar clicks onto 11 May, by which time the pair are well on their way to setting in the western sky. For anyone in the British Isles the last views will be around 1am BST on Saturday 11 May when the 6-day-old Moon lies just 1½ degrees from the heart of Praesepe and the duo will be just 10 degrees – about the span of a fist at arm’s length – above the west-northwest horizon.
This conjunction of Praesepe and the Moon favours the Eastern Seaboard of North America where, as night falls on Friday, 10 May the lunar crescent is poised to pass in front of the western edge of the star cluster. If you have a telescope, use your lowest magnification eyepiece and watch from 10pm local time until midnight as the Moon glides over the southern edge of the Beehive Cluster, occulting (passing in front of) a number of its stars.
Like cosmic ballet dancers, the stars of the Pleiades cluster are spinning, but all at different speeds. By watching these stellar dancers, NASA’s Kepler space telescope has helped amass the most complete catalogue of rotation periods for stars in a cluster. This information can provide insight into where and how planets form around these stars, and how such stars evolve.
As dusk fades to dark on the evening of Tuesday 15 November, observers in the British Isles and Western Europe can see the rising 16-day-old Moon less than 2 degrees away from Aldebaran in the constellation of Taurus. While an occultation of the star occurs around 17h UT for observers in Japan, central Asia and the Middle East, skywatchers in the UK will have to settle for a near miss.
Early risers wishing to see Venus as a dazzling ‘morning star’ need only glance low to the east in the pre-dawn sky. The planet reaches greatest brilliancy on Sunday, 20 September when, for a couple of mornings, it can be seen outshining brightest nighttime star Sirius in the southeast by a factor of seventeen times. Can you see your shadow cast by Venus?
