Bath Astronomers

August Night Sky

August brings one of the year’s major meteor showers – the Perseids. The term shower is rather is misnomer, as it implies a constant stream for its duration. What you get is a steady trickle, typically of one every few minutes. The maximum is due on the night of 11 Aug. There will be a first quarter moon, but very low in the south, so it should not provide much visual interference. All you need do is to get a comfortable seat looking skywards, ideally roughly facing east, but the direction doesn’t matter much. And then just watch for as long as you feel comfortable. If it suits you to stay up late, you should see more after midnight, as by then more of the sky you are seeing is facing the direction of travel of the earth’s orbit. The fact that meteors in this shower appear to radiate from the constellation of Perseus is just an accident of perspective from the combined velocities of the meteor shower (really debris from a comet) and the earth as their orbits around the sun intersect.

Conjunctions – close approaches of objects in the sky – are the obvious other attractions this month. On the evening of 24 August, Mars passes just a couple of degrees north of Antares, a red supergiant star in Scorpius. They will both be low in the South at 8pm, soon after sunset. Both have a strong red colour. Mars is now fading, as the earth draws away from it, but it will still be much the brighter of the two. Saturn – in between the two in brightness, but yellow in colour – will be a few degrees to the north. They should make a pleasing sight in binoculars.

The next opportunity is at about the same time 3 days later, on August 27. Jupiter and Venus will then be very close together – less than a quarter moon’s width – but they will also be extremely low on the SW horizon, not far from where the sun has just set. You will need binoculars to see them at all, but it should be interesting if you can find them. Choose your spot carefully to get the clearest and lowest horizon!