Comet C/2023 A3 Tsuchinshan-Atlas, photographed from Mount Burnett Observatory, close to Melbourne, Australia (Photo By cafuego – https://www.flickr.com/photos/cafuego/54036127092/, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=153475979)

Dear Readers, as if the Northern Lights weren’t enough excuse to watch the skies (and yes, I did miss them yet again), for the rest of the month of October there’s a good chance of seeing a comet with the naked eye; the best views, according to NASA, will be from 14th to 24th October. The Tsuchinshan-Atlas comet was first spotted by the Purple Mountain Observatory in China in 2023, and was subsequently confirmed by the Asteroid Terrestrial Impact Last Alert System (ATLAS for short). Goodness, who knew that there was a system keeping a robotic eye open for possible impacts? Not me, for sure, though I did once go on a date with a man who was completely obsessed with such things, and who had ‘forgotten his wallet’ when the time came to pay for dinner. But I digress. Fortunately, this comet (which I will be abbreviating to TA for conciseness) will definitely not be crashing into the earth and wiping us all out like so many dinosaurs, but it may be thrillingly visible until about the end of October if the weather cooperates (tonight (Sunday 13th October) looks pretty good for the southern UK at least).

Time lapse of the comet by By Cpayoub – Own work, CC0, https://commons.wikimedia.org/w/index.php?curid=148265841

Where to look for it, though? I can only speak for folks in the UK, but it seems to have already been visible in many places worldwide. The advice here is to look westwards shortly after sunset, preferably where you have a view to the horizon (not so easy in a built up area, but there we go). Where there have been clear views of the comet, it seems to have a spectacular tail. It’s always worth digging out the binoculars to scan the skies too.

Comet as seen from Gran Canaria (Photo by By Victor R. Ruiz – https://www.flickr.com/photos/rvr/54030812988/, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=153379677)

The comet was ‘born’ in the Oort Cloud, a vast spherical dome-shaped cloud of icy objects that surrounds the whole of the solar system. This is thought to be the home of ‘long-period’ comets – TA will not return to the skies above the Earth for 80,000 years, and this is the first time in human history that it’s been documented. I rather like this image of the comet from the International Space Station. There’s something about that wandering spark above the blue arc of the Earth that I find very moving.

Photo by astronaut Matthew Dominick on the International Space Station in September (NASA)

Incidentally, did you ever wonder what a comet is made of? Apparently they’re more like ‘dirty snowballs’ than anything – they are remnants of our solar system when it was first forming, and this is why scientists are so fascinated with their composition. In 2014 Rosetta was the first spacecraft to orbit a comet, Churyumov–Gerasimenko, although the lander, Philae, got stuck in a crevice and was unable to communicate with Rosetta. Nonetheless Rosetta produced some extraordinary images, and collected extraordinary quantities of data during its mission, which included flypasts of other asteroids and comets. Have a look at these!

Image of Churyumov-Gerasimenko taken by Rosetta (Photo By Justin Cowart – 67P/Churyumov-Gerasimenko – Rosetta, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=71790842)

Comet as seen from Rosetta’s NAVCAM (Photo By ESA/Rosetta/NAVCAM – https://www.flickr.com/photos/europeanspaceagency/16456721122/, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=40847079)

Space sometimes feels like unimaginable reaches of black, empty space, peopled by wandering rocks obeying their own physical rules, appearing and disappearing over the span of human history and causing wonder and speculation whenever they appear. Let’s hope that at least some of us will get a chance to view Comet C/2023 A3 Tsuchinshan-Atlas before it heads off into the depths of the solar system again.