By Martin George
Stargazers around the world are hoping for a good view of Comet Tsuchinshan–ATLAS in October. The comet is on a very elongated orbit around the Sun, and has arrived from the distant region called the Oort Cloud, a ‘reservoir’ of these icy objects. Unlike some others, such as Comet Halley, this is our only chance to see it: if it does ever return to our part of the Solar System, that will be many thousands of years from now.
The comet’s name reflects its independent discovery in China, at ‘Tsuchinshan’ (The Purple Mountain Observatory) and by one of the instruments forming part of ATLAS (the Asteroid Terrestrial-impact Last Alert System) in South Africa.
The first opportunity to see the comet will be in the first few days of October, extremely low in the sky, due east, as twilight is brightening each morning around 4:50 am. It will probably appear as a fuzzy spot of light, and if there is a tail, it will be directed up and to the left. (Comets’ tails are not formed because of their motion: they are made of material ‘blown away’ from the head of the comet by the action of the Sun.)
A more convenient period to see it may be in the few nights beginning 17 October. It will be quite low in the western evening sky, well below and to the right of Venus as twilight is fading. The chart shows Venus and the stars visible in that direction at about 8:45 pm, with the position of the comet marked for two nights to show its motion against the starry backdrop. If there is any tail visible at that stage, it is expected to be directed up and to the right.
Binoculars may be necessary to see the comet at all – but we hope it will be visible with the unaided eye! Visitors to the Ulverstone Planetarium at Hive will be shown how to find it and be given updated information on its brightness.
This chart shows the positions of the comet on 17 and 19 October, quite low in the western evening twilight around 8:45 pm. It will be seen below the constellation of Ophiuchus and to the right of Libra. Watch for brilliant Venus, and look down and to the right. Diagram by Martin George, Ulverstone Planetarium.