Comet C/2023 A3 Tsuchinshan-ATLAS. When to observe her?

In 2023, scientists from the ATLAS project in Hawaii and China's Zijinshan Astronomical Observatory almost simultaneously observed an object approaching the Sun. Examination of the trajectory showed that it most likely came from the very gravitational fringes of the solar system. The comet was named C/2023 A3 (Tsuchinshan-ATLAS) and intrigued astronomy enthusiasts, as there were indications that in 2024 it would be visible to the naked eye from Earth.

The popularizer of astronomy, Karol Wójcicki, explained on the website “With my head in the stars” that C/2023 A3 reached its perihelion – the closest distance from the Sun – on September 27. The close encounter with the star could have released masses of dust and gas, making the comet appear brighter. The object is still approaching Earth, and will be closest to our planet on October 12.

In mid-September, the comet had a brightness of +4 and was invisible to the naked eye, but this is about to change. According to the most optimistic predictions, C/2023 A3 may reach a brightness of magnitude -4, sufficient for observations without specialized equipment. The best time to observe the comet will be just after October 12, when it will be visible in the evening shortly after sunset in the Northern Hemisphere. The object should be looked for low above the western horizon.

“There is an increasing chance that it will be the brightest comet visible from the northern hemisphere in years,” Wójcicki said.

However, we should remember that predictions of comet brightness are subject to great uncertainty. As Robert Massey of the Royal Astronomical Society explained, although C/2023 A3 may be visible to the naked eye, it will be worth having a telescope or binoculars on hand.

– I think it will be an impressive comet, but probably not as easy to see as NEOWISE in 2020 or Hale-Bopp in the late 1990s – he said. The scientist added that it would be worth hunting for the comet with a camera.

– If you have a good digital SLR camera, you can take a whole series of photos, as many astrophotographers do – he said. – If you have a good cell phone camera and a small telescope, you can hold your phone up to the eyepiece and try to take a photo that way.

Interestingly, on September 29, comet C/2023 A3 was visible from Poland, but documenting it required appropriate equipment and photo processing.

This is not the only comet that can illuminate the autumn sky. At the end of September, scientists observed an object called A11bP7I, which is expected to “grab the Sun” at the end of October.