A comet may become visible to the unaided eye in the coming weeks. Here’s how you can see it

There’s a new comet in the sky that has gained a lot of attention lately over its potential to become visible to the naked eye.

Comet C/2023 A3 (Tsuchinshan–ATLAS) was discovered by observatories in China and South Africa in early 2023. Believed to have originated from the Oort Cloud — a giant spherical shell that surrounds our solar system and contains billions of icy objects — this little comet has been slowly making its way into our solar system.

At the moment, Comet C/2023 A3 is roughly 175 million kilometres from Earth. While that certainly sounds like a great distance, relatively speaking, it’s right in our neighbourhood. The comet will be closest to Earth on Oct. 12 at roughly 71 million kilometres.

There have been some reports that this could be the “comet of the century,” or the “comet of the decade,” but that’s a bit of an oversell. That’s because comets are notoriously difficult to predict: astronomers can’t predict when we will get a new comet or how bright one may get. 

The other issue is whether or not it can survive reaching perihelion — or the point in its orbit when it will be closest to the sun, which occurs on Sept. 27. At that time, it will be roughly 58.5 million kilometres from the sun.

In a recent paper entitled “The inevitable endgame of Comet Tsuchinshan-ATLAS (C/2023 A3)” published on the pre-print service arxiv.org, astronomer Zdenek Sekanina suggested that “based on its past and current performance, the comet is expected to disintegrate before reaching perihelion.” 

However, the cliché  “only time will tell” is very applicable here. We have to wait to see if it does indeed hold together after its close solar pass. 

“I’m rooting for it for sure, and I think it will survive, but we’ll have to wait and see,” said Paul Wiegert, a professor at Western University’s department of physics and astronomy in London, Ont.

“These things are very unpredictable, and as excited as we get about these things, we sort of have to temper that with the realization that, you know, it doesn’t always pan out.”

How to see it

The good news is that as more time passes, it does appear to be getting brighter. 

Right now in Canada, it can be found low in the horizon in the east just before sunrise.

For those who are looking to see it, its brightness is around 4 on the astronomical brightness scale (the brighter something is on this scale, the lower the number), meaning that you’d need to use a pair of binoculars to find it.

However, because this comet is so close to the sun, it’s important to ensure you don’t accidentally point your binoculars at the sun, as it could cause blindness.

And be warned: Don’t expect to see what you see in photographs. These are usually taken with telephoto lenses, and sometimes many images are combined, or stacked, to get a better final image.

“I would just caution everybody that that is not what you’ll be able to see at the moment, because it is still too dim to make out, especially from bright skies like Toronto,” said Elaina Hyde, associate professor and director of the Allan I. Carswell Observatory at York University’s department of physics and astronomy.

Instead, you’re more likely to see it as a faint fuzz in the sky or in binoculars. However, what remains to be seen is how bright and long the tail may become.

Some astronomers are predicting that it could get to a peak brightness of -1 or -2 on the scale, meaning it could be visible during the day. 

By the time C/2023 A3 passes closest to Earth on Oct. 12, skywatchers can find it in the evening sky, shortly after sunset. 

If you want to know exactly when for your particular location, you can use astronomy apps like Sky Safari, Star Walk, Stellarium or SkyView. Online, you can also check out The Sky Live, which allows you to put in your location and provides a live sky map for your location.

And while a comet gracing our sky has the potential to put on a beautiful show, there’s more to it than that. It’s believed that comets may have been the seeds that brought water to Earth billions of years ago.

“Anything that helps us understand the mystery of the icy outer solar system is always a good thing, and comets in particular have captured imaginations of humans probably forever,” Hyde said.

“It’s not just a dirty snowball, as some scientists like to say. Actually, some comets can have traces of basically the formation of our own solar system. [They] tell us how things were formed. Tell us why, or help us understand why the solar system looks like it does. And the bigger questions are always how did our planet end up with life? How did our planet end up with water?”