How To Find It On Saturday Before It Fades

It may no longer be a naked-eye object, but Comet Tsuchinshan-ATLAS can still be seen tonight — if you use binoculars.

Now 77 million miles (124 million kilometers) from the sun and 75 million miles (120 million kilometers) from Earth, comet A3 (also called C/2023 A3) is past its best, but at a magnitude +3.2 is still technically within the grasp of anyone with excellent eyesight observing in dark skies.

Wherever you look from, some simple sky-searching techniques will come in handy, such as my unique “cosmic coat hanger” way of locating the comet.

Don’t confuse this visible comet with the “Halloween comet,” also known as C/2024 S1 (Atlas), which is in the process of breaking-up before it gets bright. Instead, concentrate on finding comet Tsuchinshan-ATLAS.

After all, it visits the inner solar system once every 80,000 years — and it’s already on its return journey. Expect it to get fainter and smaller as it heads off into the outer solar system.

Where To See Comet Tsuchinshan-ATLAS

Although its magnitude of +3.2 makes it technically visible in a dark sky, you’ll almost certainly require binoculars or a small telescope to see it. An alternative is to photograph the comet with a camera or a smartphone; a long exposure image helps it show up more easily.

If you can, get away from light-polluted night skies. With the moon out of the post-sunset sky for the next few weeks, the sky — if clear — should be dark enough for you to find the comet.

Note: times and viewing instructions are for observers at mid-latitudes in the Northern Hemisphere. Check the exact time of sunset where you are and the comet’s setting times on Stellarium Web for times that are accurate for your exact location.

How To Locate Comet Tsuchinshan-ATLAS: Saturday, Oct. 26

Position: west, 53 degrees from the sun in Ophiuchus

Time: from 60 minutes after sunset where you are until about 22:00 local time

Magnitude: +3.2

Comet’s distance from the sun: 77 million miles (124 million kilometers)

Comet’s distance from Earth: 75 million miles (120 million kilometers)

So far, the guiding lights to find the comet have been the bright planet Venus and the bright red star Arcturus. However, as October draws to a close, both are so close to the horizon an hour after sunset that they’re unlikely to be visible. So, instead, use the stars of the Summer Triangle to find the comet. Vega in the constellation Lyra should be easy enough to find above due west and, above it, Deneb in Cygnus.

How To Find The Comet Using The Summer Triangle

Look to the left of Lyra and Deneb and you’ll see Altair in Aquila. Make a rough triangle between Altair and Vega pointing down to the horizon — the third point is roughly where the comet will be. Use a pair of binoculars.

How To Find The Comet Using Vega

Draw an imaginary line straight to the horizon from Vega and make a coat-hangar shape on the left — the comet will be the hook to the side. Scan with a pair of binoculars until you find it.

Check my feed every day this week and next for a daily “comet tracker” with sky charts and tips for viewing the comet.

Wishing you clear skies and wide eyes.