Night Sky Watch for July

Written by David Pugh

Dear CDAA Colleagues

Firstly, just a reminder that next thursday July 7th at 7.30pm will be our monthly meeting. Guest speaker Jerry Workman will be travelling up from London to give an illustrated talk on the Apollo Missions. I hope that we can have a good turn out for Jerry, one of our regular guest speakers who has not been able to come for 3 years due to the Covid situation.

Now that we are moving into July, the nights are beginning to draw out and astronomical darkness will begin again from the third week of July. Nevertheless, before that we are still able to observe in nautical twilight if we are able to stay up and observe from around midnight or just before.

Mercury is poorly placed this month but Venus is still a brilliant "morning star" before dawn low above the ENE horizon. Mars is now shining at magnitude +0.3 and move from Pisces into Aries in the morning sky. It rises at midnight by the end of the month and will be 8 arc seconds across. This means that a 200mm (8inch) scope or larger should be able to show surface markings and it reaches 37 degrees altitude.

Jupiter, at mag -2.7 in Cetus, precedes Mars in the eastern morning sky. By the end of the month Jupiter rises before midnight. Saturn, in Capricornus, rises by late evening mid month and is at opposition next month. Uranus keeps Mars for company in Aries and Mars closes in on the ice giant for a pre-dawn conjunction on the 31st. Neptune rises among the stars of Pisces before midnight in the eastern sky and can be viewed with binoculars or a telescope.

The summer constellations will become more prominent as July proceeds with Vega, for example, almost overhead. However, as I covered the constellations in and around the Summer Triangle in my June talk I would like to take you more to the south. Obviously this means you need access to close to the southern horizon.

Here in particular you come to Sagittarius the Archer, its brightest stars forming a teapot shaped asterism. Sagittarius includes the centre of our Milky Way galaxy but you need to travel south e.g to the Mediterranean to get a good view of the star clouds there. However, perhaps surprisingly you can view from Clacton two of its famous nebulae in northern Sagitarrius; M8 the Lagoon nebula and star cluster and M20 the Triffid nebula above it. Visually the nebulae themselves are difficult with binoculars or a telescope from the UK because of their low altitude but you can see the associated star clusters and can image both nebulae satisfactorily using a light pollution filter.

Further north other worthwhile objects only visible in the evening at this time of year include M16 the Eagle Nebula in Serpens Cauda, M17 the Swan or Omega nebula in N.Sagittarius and M11 the Wild Duck Cluster in Scutum. All of these are further from the southern horizon at culmination and thus easier to observe. M11 is a particularly rich open star cluster well worth a look.

Wishing you all clear skies.

Best Wishes

David