A once-in-80,000-years visitor lights up the sky
Comet A3 Tsuchinshan-ATLAS, an icy visitor from the distant Oort Cloud, is making its closest approach to Earth on Saturday, October 12, 2024. The comet, which orbits the Sun once every 80,000 years, will be visible to the naked eye in the western sky after sunset, marking a rare and spectacular celestial event. It was initially detected in 2023 by astronomers at China’s Purple Mountain Observatory and an ATLAS (Asteroid Terrestrial-impact Last Alert System) telescope located in South Africa.
Best time to see the comet
On October 12, the comet will pass within 43.9 million miles of Earth, reaching its closest point at 11:39 a.m. ET. Stargazers should look toward the western horizon about 45 minutes after sunset, where the comet will appear just 6 degrees above the west-southwest horizon. It will remain visible for roughly 45 minutes before setting.
The comet will initially appear low on the western horizon in the glow of twilight about 45 minutes after sunset each day starting Saturday, Oct. 12, through the end of the month.
In the days following, the comet will rise higher in the sky, offering an even better view. By October 19, it will be 30 degrees above the horizon before it begins to fade from view, disappearing from the naked eye.
What to expect
Comet A3 Tsuchinshan-ATLAS will be one of the largest visible objects in the night sky during this period, second only to the Moon. Its head measures an impressive 130,000 miles in diameter, while its tail of ice and dust stretches as long as 18 million miles.
The comet’s tail will point directly at Earth on October 12, giving observers a unique view. Each night, the tail will move eastward, creating a different visual experience as it climbs higher into the sky.
Where to look and how to prepare
This weekend offers the best opportunity to see Comet A3 Tsuchinshan-ATLAS for those in the Northern Hemisphere. Previously, the comet had only been visible in the Southern Hemisphere and Tropics, but now, viewers across the Northern Hemisphere can witness this rare event.
To catch the best glimpse, head outdoors just after sunset and look towards the western sky. The comet will remain visible for several days, with the best views on October 12. After that, it will rise slightly higher each night but gradually fade as it moves away from Earth.
This cosmic visitor may not be back for another 80,000 years, so make sure to witness this extraordinary moment in space.