Dark Skies July Update
The sky chart shows the night sky for mid July at 22:00. Very low on the north-west horizon as the sun sets, we'll get a chance to see Mercury and Venus in a close pairing. This will be a difficult sight to catch in the still bright twilight skies but don't be tempted to sweep the area with binoculars unless the sun has completely set below the horizon. Mercury will only be around for a week or so, but Venus will linger in the twilight zone for a couple of months to come, before finally clawing it's way into the evening skies late in the year.
The next planet around the western skies is Jupiter, still blazing away below the constellation of Leo, but slowly descending into the western horizon and becoming lost to view in the solar glare during August.
Looking towards the southern horizon, we still have ruddy coloured Mars and Saturn on show. Mars is slowly dropping in brightness as we (the Earth), and Mars draw apart from each other in our respective orbits around the sun. An effect of this is that Mars will rapidly approach Saturn over the next month or two and this pairing its closest in the middle of August. Possibly a nice photo opportunity there!
At this time of the year, the Milky Way starts to impose itself on our skies again. Extending from north to south almost overhead at the moment, you are looking along the major axis of our own galaxy, towards the galactic centre in Sagittarius where the main concentration of stars is to be found. With our dark skies, look out for a feature called “the Cygnus rift”. It's a band of dark interstellar dust that lies between us and the more distant stars of our galaxy, obscuring them from view, causing this “rift” in the Milky Way. You can see it on the sky chart, starting in the constellation of Cygnus, running southwards through Sagitta and down towards the galactic centre of Sagittarius.
For those with binoculars or telescopes, here is a beautiful summer target to look for: Locate the constellation of Hercules in the sky, roughly due south and almost overhead. The bright star Vega is something of a guide to the correct area. In the “middle” of Hercules is a mis-shapen square of stars often called the “keystone”. On the right hand or western edge of this pattern and two thirds of the way up is an object called a globular cluster. This one is identified as M13, as it is the thirteenth object in a catalogue of the sky made by Charles Messier – hence the “M”. It's actually a cluster of some 200,000+ stars that orbit together outside our own galaxy, and is one of many such globular clusters visible with binoculars or telescopes. The photo below shows the keystone area with the cluster circled and identified with this diary to help you find it. If your keen, try and see another example of a globular cluster close by; M92.
Clear skies and good hunting!