Currently visible just before sunrise, the comet of the year will soon be visible after sunset and will remain trackable until late October.
Credit: Gianni Tumino
Comet Tsuchinshan-ATLASAlso known by its catalog designation C/2023 A3, it now has a magnitude of 2.2 in the morning sky. But if you're not an early riser, you'll soon be able to rejoice: it will be visible in the night sky starting October 14.
On that date, the comet will be at the eastern end of the constellation Virgo. On the 15th you will have crossed the border into Serpens and, for Eastern Time Zone observers, will be just over 1° south of the globular cluster M5. If the comet is bright enough, both objects could be seen simultaneously through binoculars. In the western US, the movement of Tsuchinshan-ATLAS will place it slightly southeast of M5.
When should you look for the comet
The brightness of comets is notoriously difficult to predict, but if the main body of Tsuchinshan-ATLAS holds together, we could be treated to a bright celestial sight. Unfortunately, each observer should consider when to observe the comet for two reasons.
First, there are the moon. It will be on October 17, right in the middle of Tsuchinshan-ATLAS's best viewing period. After that date, our satellite will rise later each night, which will make observing the comet much easier.
Secondly, the comet never rises high in the sky. On October 15, Tsuchinshan-ATLAS will have an altitude of 16° in the west one hour after sunset. On the 18th (the night after the Full Moon), it will be a more respectable (and easier to spot) 25° above the horizon.
Where should you look for the comet
Tsuchinshan-ATLAS will move to the Ophiuchus constellation on October 19, and from this date the Moon will no longer hinder observation. One hour after sunset, the comet will have an altitude of 28° in the west and will be located quite close to the magnitude 3.8 star Marfik (Lambda (λ) Ophiuchi). Observers expect it to be much brighter than the star.
The comet will continue passing through Ophiuchus and, on the 28th, it will be between two of the brightest stars in that constellation: Cebelrai of magnitude 2.8 and Muliphen (Beta (β) and Gamma (γ) Ophiuchi of magnitude 3.7). The pair of stars is 2° apart. That night, one hour after sunset, the comet will be at an altitude of 40° in the southwest.
Prolific comet discoverer David Levy likes to say: “Comets are like cats. “They both have tails and it is difficult to predict what they will do.” Let's hope this comet puts on a great show.
Related: Astronomy January 2023 issue of the magazine: The world of comets
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