Astrophotographers and skywatchers will get a once-in-a-lifetime opportunity to witness Comet Tsuchinshan-ATLAS (C/2023 A3) as it makes its closest pass to Earth this week.

This rare celestial visitor, originating from the distant Oort Cloud, will be visible in the night sky before it vanishes into the depths of space for possibly the last time.

Comet Tsuchinshan-ATLAS was first detected in January 2023 by astronomers at China's Purple Mountain Observatory and independently observed by the Asteroid Terrestrial-Impact Last Alert System (ATLAS) in South Africa.

The comet, which takes approximately 80,000 years to orbit the Sun, will reach its brightest point today (October 9), when sunlight is scattered by its dusty tail, enhancing its visibility in an effect known as forward scattering. This will be the best chance to see the comet with the naked eye, binoculars, or a small telescope.

The comet is best viewed in a dark location with an unobstructed view of the western horizon. A few minutes after sunset, look low in the sky where the Sun has set. The comet will appear fuzzier than nearby stars, and it may be challenging to spot against the remaining twilight glow. Binoculars will help.

The comet will be visible from both hemispheres, although those in the Southern Hemisphere will have the best view initially. After its brightest point, the comet will rise higher in the sky throughout October, becoming easier to spot in the evening. However, its brightness will fade as it moves away from Earth and the Sun. Moonlight, especially during the full Supermoon on October 17, could affect viewing conditions, so aim for nights when the Moon is less bright.

For the best viewing conditions, find a location away from city lights to observe the comet as it transitions into evening prominence between October 12 and October 26. During this time, it will climb higher above the western horizon each night. As the comet approaches Earth, its tail will appear to pivot and extend dramatically. There may even be a chance to see a rare optical illusion known as an "anti-tail," where dust left behind by the comet appears to extend in the opposite direction of the usual tail.

This could be humanity's last chance to witness Comet Tsuchinshan-ATLAS before it potentially leaves our solar system for good.