A Naked-Eye Comet Is Coming Next Week — When To See Comet A3

Comet C/2023 A3 (Tsuchinshan–ATLAS) — also known as Comet A3 — looks set to shine brightly enough to be visible to the naked eye in late Sept. and early Oct.

It comes in the wake of April's 12P/Pons–Brooks, 2023’s “green comet,” and 2020’s comet NEOWISE and in the same year as April’s total solar eclipse and May’s best aurora since 2002.

Here’s everything you need to know about comet A3, from when to see it to where to find it in the night sky this September and October.

When And Where To See Comet A3: Southern Hemisphere

Your hemisphere will affect when you'll get the best view of comet A3. For those in the southern hemisphere, the best views will likely be before sunrise around its perihelion on Sept. 27. That's the closest it will get to the sun, so it will likely be at its brightest, while in the constellation Leo and Sextans.

When And Where To See Comet A3: Northern Hemisphere

Those in the northern hemisphere will likely have their best chance to see comet A3 in post-sunset skies around Oct. 12, when it will have re-emerged from the sun’s glare and get to its closest to Earth (at about 44 million miles, so it's perfectly safe!).

Comet A3 will be in the constellation Ophiuchus above the west, and gradually fade as the month progresses.

However, those in the northern hemisphere do have a few other options.

MORE FOR YOU
Today’s NYT Mini Crossword Clues And Answers For Friday, September 20th
Google Chrome Says Goodbye To Passwords On Windows, Mac, Linux, Android
Here’s How Much Every Living Former President Earned After Leaving The White House

When And Where To See Comet A3 This Week

Close to its perihelion on Sept. 27 and until Oct. 2, comet A3 should be visible one hour before sunrise from the northern hemisphere (here's a handy sunrise and sunset calculator).

Here's a sky chart for one hour before sunrise on Sept. 27, as seen from the U.S. It will be a challenging observation — it will be very low on the horizon — and it will sink closer to the horizon with each passing morning, so grab a look while you can.

What Comet A3 Will Look Like

Comet A3 is likely to have a tail of dust and ice— and possibly two tails, one whiteish and one blueish. By lucky chance, its orientation in the inner solar system means its tail may reflect more light toward Earth, making it appear brighter. This is called forward scattering by astronomers, and it should play in our favor.

How Best To See Comet A3

To successfully see comet A3, you’ll need:

• Clear skies, which are less likely when viewing objects low on the horizon because you’re looking across the planet.
• A view low to the east in late Sept. and early Oct. and low to the west in mid-Oct.
• To be in a location away from light pollution, which can hugely lessen the impact of seeing a comet. Find a Dark Sky Place or scout a dark location near you using a light pollution ma (bearing in mind that you may not be the only one).

What Is Comet A3?

Comet A3 is a long-period comet from the Oort Cloud, a sphere around our solar system home to millions of comets. It's in an orbit of roughly 80,000 years, so this is your only chance to see it.

Comet A3 was discovered in January 2023 by astronomers at China’s Tsuchinshan Observatory and South Africa’s Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope.

Wishing you clear skies and wide eyes.