2 weeks Ago
Can comet Tsuchinshan-ATLAS still be seen? Yes, but it’s now past being a bright, naked-eye object after sunset. To see comet A3 (also called C/2023 A3) you’ll now need a pair of binoculars. Now a 4th magnitude object, it’s just beyond the easy reach of the naked eye, and if you’re observing anywhere aside from under an ultra-dark sky, optical aids will be needed.
However, hopes for the comet are up because the moon is down. With a New Moon on Friday, the night skies this week are perfect for spotting the comet against a black sky. As luck would have it, the comet is close to the famous “Summer Triangle” asterism of three bright stars where the Milky Way flows to the horizon, so you may get two celestial sights for the price of one.
There’s even a possibility of the comet being in the sky at the same time as the Northern Lights, if the solar activity spiking this week translates to geomagnetic storms. Seeing comet Tsuchinshan-ATLAS is easy if you know how, so here are two ways to find it — one an hour after sunset and the other two hours, before the comet sets. Where Is Comet Tsuchinshan-ATLAS? Now 87 million miles (140 million kilometers) from Earth and shining at a magnitude of +4 in the constellation Ophiuchus, the comet is rapidly getting fainter and smaller, and to get any kind of impressive view will require a pair of binoculars or a small telescope.
Another way to see it is to photograph the comet with a camera or a smartphone because a long exposure image of a few seconds will show it more easily. 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: Wednesday, Oct. 30 Position: west, 55 degrees from the sun in Ophiuchus Time: from 60 minutes after sunset until about 22:30 local time Magnitude: +4 Comet’s distance from the sun: 84 million miles (135 million kilometers) Comet’s distance from Earth: 87 million miles (140 million kilometers) How To Find The Comet Using Venus If you look southwest about an hour after sunset, you’ll likely see the bright planet Venus. That’s your guiding light to the comet.
Look above Venus for the bright star Vega in the constellation Lyra. Look halfway between Venus and Vega, and you should find the comet, though probably only if you use a pair of binoculars. How To Find The Comet Using The Summer Triangle Since Venus will sink soon after sunset — or you may have horizon clouds or mountains to contend with — you can also use the stars of the Summer Triangle, of which Vega is one.
Find the other two that make up the famous asterism — Deneb in Cygnus, above Vega, and Altair in Aquila, to the left. Now, make a rough triangle between Altair and Vega by pointing down to the horizon. The third point is roughly where the comet will be.
You'll need binoculars to see it — as well as a dark, clear sky. What Is Comet Tsuchinshan-ATLAS? It’s a long-period comet from the Oort Cloud, a sphere around the solar system that’s home to millions of comets. Astronomers think it loops around the sun once every 80,000 years.
Its coma is about 130,000 miles (209,000 kilometers) in diameter, and its tail extends around 18 million miles (29 million kilometers) into space. Check my feed for a daily “comet tracker,” with useful sky charts and tips for viewing the comet. Wishing you clear skies and wide eyes.
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