Night Sky Watch for May

Written by David Pugh

Dear CDAA Colleagues

Now that we are entering early summer the nights are very much drawing out. By the third week in May we will run out of astronomical darkness, (when the Sun is more than 18 degrees below our local horizon), and that will not return until the third week in July. So make the most of the first three weeks of this month although it does mean observing quite late for a reasonably dark sky. However, there a number of events this month in civil twilight, including an eclipse of the Moon, so read on.

Mercury continues last month's best evening showing for the first 10 days of May. If you have a low WNW horizon you can see Mercury (mag +0.7) shortly after sunset with binoculars. But make sure the Sun has truly set to avoid serious eye damage! On May 2 Mercury will lay only 2.7 degrees NW of a young crescent Moon.

For early risers there will be a close conjunction of the brightest planets Venus and Jupiter in the pre-dawn sky of May 1. The two planets will be only 21' apart but you will need a clear ESE horizon as they will only be 10 degrees high at sunrise. For the rest of the month Venus is not well placed, lying low in the pre-dawn sky.

Mars, also low in the pre-dawn sky (mag +0.8) tracks eastwards from Aquarius into Pisces. In the pre-dawn of May 29 there is a close conjunction (36') of Mars with Jupiter in the ESE at about 14 degrees high at sunrise. Jupiter is brilliant (mag -2.2) in the run up to dawn, close to Venus and Mars, hence the conjunctions.

Saturn (mag+0.8) is low in Capricornus in the pre-dawn sky, further west than the other planets. Uranus is in conjunction with the Sun and not visible this month. Neptune (mag 7.9) slowly emerges from the Sun's glare in the pre-dawn sky and lies close(0.6 degrees N) to Mars on May 17.

The Eta Aquarid meteor shower peaks on the morning of May 5 without any interference from moonlight. Although it has a Zenithal Hourly Rate of 10 - 30 meteors, the radiant near the "water jar" asterism in Aquarius is low in the ESE about 4am BST.

There is a new first time comet from the Oort Cloud called 2021 03 PanSTARRS that may reach mag 6, visible in binoculars, by the beginning of May. There is a chart in Astronomy Now and also on-line but essentially it moves north from the Pleiades up the chain of stars forming southern Perseus. It will be low in the WNW after sunset and difficult.

So for the Moon. There will be a Total Eclipse of the Moon on the morning of 16th May!! Yes you heard it right - but totality begins at 4.29am BST in civil twilight when the Moon is barely 4 degrees above the SW horizon from the south of England. The Sun rises at 5.10am BST. UK observers will have a better chance at the partial phase that begins at 3.29am BST when the Moon lies 11 degrees high from London. The best view of totality will be from the Americas.

On the deep sky front, whilst we are running out of astronomical darkness, some objects are not too bad in lighter skies such as planetary nebulae and globular clusters. Try for M13 and M92 globular clusters in Hercules in the eastern sky for starters or M97 the Owl Nebula planetary nebula as more of a challenge but overhead in the Plough. M44 the Beehive cluster in Cancer in the south is bright enough but very large requiring binoculars or a small telescope at low powers. Similarly, you could try the Coma Cluster Melotte 111 with binoculars in the faint constellation Coma Berenices (Berenice's Hair).

Good Hunting and just a reminder that the May monthly meeting is this coming thursday May 4th when our chairman Mike will be telling you about all the latest astronomy news and research..