The spear-shaped anti-tail of Comet Tsuchinshan-ATLAS (C/2023 A3) is on full display in this image taken on October 14. Credit: Chris Schur
Comet C/2023 A3, also known as Tsuchinshan-ATLAS, has been in the evening sky for a week now. If you haven’t seen it, it’s understandable because there was also a bright Moon in the sky. But the Moon is full tonight (October 17) and will rise later tomorrow (October 18) and each night thereafter. So, try to catch this beautiful celestial visitor before it moves so far away from Earth that only telescopes will be able to capture it.
To give you an idea of how easy it is to spot, last night in Tucson, Arizona, I saw it in the western sky even though the sky was half full of clouds and the light from the nearly full moon in the east made it bright. I first spotted it with binoculars, but after 20 minutes the part of the sky where the comet was located had cleared, and I could see it without any optical aid.
No, it wasn’t as bright as the Moon or Venus, which was the bright stellar object to its left, but I could easily see the comet’s tail curving up and to the left. Through binoculars, the head appeared blurry and the tail fanned out, forming an angle of about 30°.
If your sky is clear, you will see it after the glow of evening twilight has almost faded. Last night in Tucson it was visible just 30 minutes after sunset. But at mid-latitudes or higher, where the Sun sets at a slower rate, it could take an hour or more. Find the west. Start with binoculars (a 7×50 model works great) pointed slightly to the left of west. Then slowly raise them until the area of the sky you are looking at is as high above the horizon as twice the width of your fist held at arm’s length. This is approximately equivalent to 20°. You’re close. Now slowly move the binoculars. You will see stars that you can focus on. Soon an object will appear as if it were blurry. Oh, and it also has a tail. Congratulations, that’s Tsuchinshan-ATLAS.
