Grab Your Binoculars for Comet ATLAS’s Brief Sunset Show

Comet ATLAS (C/2024 G3) is now bright enough to see in ordinary binoculars at dusk for observers at mid-northern latitudes. Its altitude is very low, but if you find a location with an unobstructed view of the southwestern horizon and your sky is haze-free, this frozen confection is yours for the taking.

Mind that the viewing window is unusually narrow. The comet just transitioned into the evening sky on January 14th and will stick around only until January 20th or so. Thereafter, it dips back under the horizon, where Southern Hemisphere skywatchers will have the best viewing circumstances for the remainder of its apparition.

I had pretty much written off observing Comet ATLAS at my northern latitude. But its impressive appearance in imagery from the orbiting Solar and Heliospheric Observatory (SOHO) and daytime sightings by amateurs forced me to reconsider. I tried twice during daytime with my camera, telescope and binoculars — without success — but hit the jackpot on the evening of January 14th. A high pressure cell had cleared the sky of haze and clouds from horizon to horizon. From my viewing spot overlooking a frozen lake, Venus gleamed hopefully as the last shard of Sun disappeared below the distant trees.

My app showed that 15 minutes after sunset the comet would be about 3.5° high the same time the Sun was 3° below the horizon. Since another northern observer had caught sight of C/2024 G3 under these circumstances with binoculars, I might, too. I first aimed my 10×50s at Venus to make sure to make sure the focus was sharp, then started sweeping within a few degrees of the horizon. At 5:03 p.m., 18 minutes after sunset, a bright, white dot jumped out from the sea of dark “floaters” that drifted across my field of vision. I gasped out loud. Whoa — was that the comet?! Indeed.

Once found amid the blankness, the comet was incredibly easy to see. First things first: I lined it up with a distant tree to make sure I wouldn’t lose sight of the object. The comet’s head was small, very condensed and bright, with a streak-like tail about 20′ long pointing back to the east. The whole of it appeared tiny and sleek, as if it were far, far away. I watched and photographed this plucked plum for about 20 minutes until it disappeared in the trees. Estimating the comet’s magnitude was tricky because there were no references, but based on memories of observing bright planets in deep twilight I settled on –2. It was not visible with the naked eye.

Unlike last fall’s Comet Tsuchinshan-ATLAS (C/2023 A3), which became increasingly impressive night by night as its altitude climbed in the western sky, Comet C/2024 G3 will hover at virtually the same altitude the next few nights before it slides out of view. That and the fact that it’s now departing the Sun and slowly fading likely mean that the comet will be a binocular object for most of us except those with exceptional skies.

That said, it may be possible to see its tail sticking above the horizon through about January 26th, if not visually then photographically. Sounds like a great project for anyone with a digital camera. Meanwhile, Southern Hemisphere comet-watchers are eager for Comet ATLAS to gain altitude and punch through the twilight. That should happen either today (January 15th) or tomorrow.

Given its brief viewing window, my observation may be a one-off. If so, that’s life. My hope is that you get to see the comet and experience a similar joy. Good luck!