Could Comet A3 be visible to the naked eye this year?

Sky watchers are buzzing over a new comet, known as A3, which is about to become visible in the northern hemisphere - and could be visible to the naked eye, even in daylight.

Some have even suggested that the comet, known more formally as C/2023 A3 (Tsuchinshan-ATLAS) could be the ‘brightest comet in 100 years’ when it becomes more visible in early October.

But some scientists have poured cold water on the claims, suggesting that the object faces ‘inevitable collapse’ when it reaches perihelion (the moment in its journey when it is closest to the sun), which will happen on September 27.

For now, the icy ball is getting brighter, and astronomers in the southern hemisphere have captured photos of it.

NASA astronaut Matthew Dominick photographed the comet from the International Space Station on September 19th, saying, "So far Comet Tsuchinshan-ATLAS looks like a fuzzy star to the naked eye, but with a 200mm, f2 lens at 1/8s exposure you can really start to see it!' This comet is going to make for some really cool images as it gets closer to the sun."

When was Comet A3 spotted?

The comet was first spotted independently by astronomers at two observatories: Asteroid Terrestrial-impact Last Alert System (ATLAS) spotted it on February 22 2023.

Astronomers at China’s Purple Mountain (Tsuchinshan) Observatory in China spotted the comet in images from January 9 2023, hence the name Tsuchinshan-ATLAS.

It completes an orbit around the sun every 80,660 years, astronomers believe, according to EarthSky.

Where is it now?

It’s currently visible from the southern hemisphere in the constellation of Sextans, according to The Sky Live.

It’s roughly 101 million miles from Earth at present, and moves in the opposite direction from most objects in the solar system.

On September 27, it will reach its closest point to the Sun (known as its perihelion) at 36 million miles from the sun, according to EarthSky.

At this point, many comets break up due to the sun’s rays affecting their icy bodies, and some experts believe this will be what happens to Comet A3.

When could it be visible to the naked eye?

The comet is brightening rapidly, and, after passing the sun on September 27, will fly past Earth on October 12th.

It’s expected to be brightest on October 9th, when the light from the sun will be ‘forward scattered’ by dust from Comet A3, according to SpaceWeather.com.

Different scientists have different predictions for what will happen, and in the most optimistic predictions, it could be visible to the naked eye or even in daylight, according to Forbes.

Why do some scientists think this won’t happen?

In a pre-print paper titled ‘Inevitable Endgame of Comet Tsuchinshan-ATLAS (C/2023 A3)', revered Czech-American astronomer Zdeněk Sekanina suggests that the comet will not survive perihelion.

Sekanina writes, "based on its past and current performance, the comet is expected to disintegrate before reaching perihelion. Independent lines of evidence point to its forthcoming inevitable collapse".

Sekanina, who was involved in investigations around Halley’s comet, believes that the comet is already in an "advanced phase of fragmentation".