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.
As dusk fades to dark on Saturday, 11 June, observers in the British Isles should look low in the western sky to see the 7-day-old waxing crescent Moon and Jupiter less than 3 degrees apart, within the same binocular field of view. Get your observations in now as the solar system’s largest planet is poised to leave the celestial stage during the summer.
In the dawn twilight of Friday, 4 December observers in the British Isles and Western Europe can see the 23-day-old waning crescent Moon just 2.5 degrees (half a 10×50 binocular field of view) below largest planet Jupiter in the constellation Leo high in the southern sky. And if you have a telescope, Jupiter’s largest moon plays hide and seek.
A waxing crescent Moon hanging low above the horizon in evening twilight is always a pleasant sight to behold, but observers in the UK watching the 4-day-old Moon through a telescope around 40 minutes after sunset on Sunday, 24 September have an additional treat in store in the form of an occultation of naked-eye star gamma (γ) Librae.
