A conjunction occurs when two or more planets appear close to each other in the night sky.
With Saturn improving as a morning object in the constellation of Capricornus, we are also treated to a total lunar eclipse as the Moon sets mid-month. Alternatively we have two evening planetary stars gracing our skies during the early part of the month as the brilliant Venus is joined by its fainter little sibling Mercury.
Star-wise, orange-coloured Arcturus, the principal star of Bootes, the herdsman, forms a giant triangle with two blue-white stars, Spica in Virgo and Leo’s shining light Regulus.
The 16th sees a total lunar eclipse when the whole Moon enters Earth's shadow (umbra). Some sunlight still reaches the Moon, but first it goes through Earth's atmosphere. The atmosphere filters out most of the Sun’s blue light, so the Moon looks red.
The main event starts at 3.27am with totality at 4.29am. Unfortunately the Moon sets at 5.14am, so you will need an unobstructed south western horizon for the best views.
This month’s meteor shower is the Eta Aquarids which can produce up to 30 shooting stars per hour given ideal conditions. Tiny pieces of Halley’s Comet ‘burn’ up in the Earth’s atmosphere, which can be seen flying across the sky in the early hours of the 6th.
The Eta Aquarids is one of two meteor showers created by debris left behind by Comet Halley. The Earth passes through Halley's path around the Sun a second time in October, creating the Orionid meteor shower.
Comet Halley takes around 76 years to make a complete revolution around the Sun, with the next time being 2061 when it will be visible from Earth. The waxing crescent Moon will set early in the evening, leaving dark skies for what should be an excellent show. Best viewing will be from a dark location after midnight. Meteors will radiate from the constellation Aquarius, but can appear anywhere in the sky.
For lovers of constellations the cosmic dragon, Draco, is worth exploring as it writhes between the two bears in the northern sky. Draco is associated with the 12 labours of Hercules.
The brightest star, Eltanin, lies in the dragon's head at a distance of 154 lightyears, while Thuban, 300 lightyears away, lies in the tail of the dragon.
Around 2800BC Thuban was identified as our Pole Star until it was replaced by the more familiar Polaris. This movement or ‘precession’ is a result of the Earth’s axis swinging around, like the toppling of a spinning top.
We can look forward to AD13600 when the brilliant Vega will take over the pole. Oh, and in AD 22600 it will be Thuban’s turn again.
Steve Szwajkun FRAS, Shropshire Astronomical Society