C/2023 A3 (Tsuchinshan-ATLAS): Will It Be The Next Great Comet?

~7 min

In early 2023, the ATLAS survey and Purple Mountain Observatory detected a comet that was named C/2023 A3 (Tsuchinshan-ATLAS). It is expected to reach naked-eye visibility by October 2024 and become as bright as the most luminous stars! Here is everything that is known about this comet so far.


What is the comet C/2023 A3 (Tsuchinshan-ATLAS)?

On February 22, 2023, the ATLAS telescope in South Africa detected a new faint object that was proven to be a comet. It was temporarily designated as A10SVYR. The comet was also independently captured by a telescope at Purple Mountain Observatory (Zijinshan Astronomical Observatory) on January 9, 2023. It was added to the list of objects awaiting confirmation, but after no follow-up observations were reported, it was removed on January 30, 2023, and was considered lost. Based on the comet naming system, the comet received the names of both observatories and was officially named C/2023 A3 (Tsuchinshan-ATLAS).

Shortly after its discovery, observations up to December 2022 were found in the archives of the Minor Planet Center, which gave us a little more information about the comet. Looks like it’s a long-period comet with an orbital period of 26,000 years. It also seems to have a fairly large nucleus.

By the end of July 2023, C/2023 A3 (Tsuchinshan-ATLAS) will be 5.86 AU from the Sun and will be slowly approaching it, becoming brighter. It is predicted to reach maximum brightness in October 2024. According to the calculations by the SETI institute, the comet’s peak brightness can range from a magnitude of -0.1 to -6.6, which is comparable to the luminosity of the brightest stars. By comparison, the comet Hale-Bopp, one of the most widely observed comets of the 20th century, had a peak magnitude of -1.8. The so-called green comet C/2022 E3 (ZTF), which was trending at the beginning of 2023, reached a maximum magnitude of 5.4. The famous NEOWISE (C/2020 F3) peaked at 0.9.

What makes C/2023 A3 (Tsuchinshan-ATLAS) special?

First of all, C/2023 A3 (Tsuchinshan-ATLAS) is expected to grow a beautiful cometary tail; fainter comets usually don’t have prominent tails at all. After passing by the Sun at a distance similar to Mercury's orbit, C/2023 A3's coma of dust and ice will heat up considerably. As the ice particles evaporate, they will quickly escape into space, taking with them a large amount of dust that will extend into a long, bright tail. As history shows, comets that pass close to the Sun have the most impressive tails, formed soon after being "roasted" by the Sun's heat. And this is the case with comet C/2023 A3!

Comet McNaught over the Pacific Ocean

In addition, C/2023 A3 (Tsuchinshan-ATLAS) will favor the Northern Hemisphere being perfectly visible there. The last time an exceptionally bright comet was visible from the northern latitudes was in 1997 when Comet Hale-Bopp lit up the sky.

What does the name of the comet C/2023 A3 (Tsuchinshan-ATLAS) mean?

The name of the comet contains data about where and when the comet was first seen:

  • The letter C indicates a non-periodic comet – comets of this type originate from the Oort cloud and may pass through the Solar System only once or take from 200 to thousands of years to orbit the Sun;
  • 2023 A3 means the comet was discovered in 2023, in the first half of January (this corresponds to the letter A in the IAU comet naming system), and was the third such object discovered in the same period;
  • Tsuchinshan-ATLAS means the discovery was made using telescopes of the Purple Mountain Observatory (Zijinshan Astronomical Observatory) and Asteroid Terrestrial-impact Last Alert System (ATLAS).

Best time to observe C/2023 A3 (Tsuchinshan-ATLAS)

C/2023 A3 (Tsuchinshan-ATLAS) favors the Northern Hemisphere, where it will be visible to the naked eye in October 2024. It’s hard to predict the exact brightness of the comet — most tend to think it will be about 0-1 magnitude.

On September 27, the comet will make its closest approach to the Sun (0.39 AU), and there will be a chance to catch it during the day. Due to the effect of forward scattering, C/2023 A3 (Tsuchinshan-ATLAS) might brighten up to -4.0 magnitude.

C/2023 A3 magnitude
The red curve is the estimated magnitude of the comet. The gray curve is based on the absolute magnitude. The green curve shows the effect of forward scattering, which occurs when the comet is between the Earth and the Sun. For more information, see the C/2023 A3 (Tsuchinshan-ATLAS) page on astro.vanbuitenen.nl.

After the perihelion, C/2023 A3 (Tsuchinshan-ATLAS) will disappear for a while and reappear in the evening sky in early October 2024. It will remain an evening object until the end of the month. On October 12, 2024, it will pass close to the Earth (0.48 AU) and should be easily visible around that time. Then the comet will fade rapidly, and by mid-November, it will no longer be visible to the naked eye. Observers will only be able to see it with binoculars and telescopes.

Is the comet C/2023 A3 (Tsuchinshan-ATLAS) visible now?

Currently, the comet stays within the 16th magnitude range and is visible through a big telescope. It rises in the daylight hours and sets around midnight local time. Northern Hemisphere observers can spot it after sunset in the constellation Virgo. You can track C/2023 A3 with the Sky Tonight free app. From August 2023, the comet will travel the sky during the daytime and, therefore, be almost invisible until next February.

Photo of C/2023 A3 (Tsuchinshan-ATLAS)
This image of C/2023 A3 (Tsuchinshan-ATLAS) was taken on April 9, 2023, at Nishi Ward, Kumamoto City, Japan.

C/2023 A3 (Tsuchinshan-ATLAS) visibility forecast for 2024

Here are some predictions for 2024 monthly visibility:

  • January: not visible
  • February: 14 magnitude, visible in the second half of the night;
  • March: 13 magnitude, visible from midnight;
  • April: 12 magnitude, visible in the evening;
  • May: 10-11 magnitude, visible in the evening;
  • June: 9-10 magnitude, favors the Southern Hemisphere. Bad observing conditions in the Northern Hemisphere due to bright summer nights and lower declination from the Sun;
  • July: 8-9 magnitude, still favoring Southern Hemisphere, evening visibility;
  • August: 4 magnitude by the end of the month, but too close to the Sun;
  • September: 3-4 magnitude, moves away from the Sun and begins to appear in the morning sky in the Southern Hemisphere. Short observation window, a good opportunity for capturing the comet’s tail. From September 27 to October 2, it appears in the morning in the Northern Hemisphere.
  • October: the best month for observations in the Northern Hemisphere.

After October, the comet will gradually fade.

Please note that comets are very unpredictable space objects, and data (especially apparent magnitude) can change quickly. However, we’ll do our best to keep you up to date.

C/2023 A3 (Tsuchinshan-ATLAS) approaching the Earth in 2024: path through the Solar System

Here, you can get a month-by-month guide on the comet’s journey through the Solar System in 2024. We also made a video to visualize the comet's trajectory in space. Watch it to see how the comet's brightness and location will change over time.

  • January 2024: comet C/2023 A3 will pass the orbits of Saturn and Jupiter and will be on its way to Mars. By the end of the month, the distance between the comet and the Earth will be 3.88 AU.

  • February-July 2024: for six months, C/2023 A3 will be traveling between the orbits of Jupiter and Mars. By the end of this period, the comet will be 2.04 AU away from the Earth.

  • August 2024: comet C/2023 A3 will reach the area between the Earth and Mars. By the end of the month, the comet will approach the Earth as close as 1.76 AU.

  • September 2024: comet C/2023 A3 will enter Venus’s orbit. On September 27, the comet will pass perihelion, meaning it will come the closest to the Sun, at a distance of 0.39 AU. During this period, the comet may break apart under the impact of the high temperature.

  • October 2024: if C/2023 A3 survives perihelion, then on October 12, it will come the closest to the Earth and will be at a distance of 0.48 AU from our planet. It will reach maximum brightness and be observable even with the naked eye.

  • November 2024: C/2023 A3 will gradually lose its brightness as it will move away from the Earth. By the end of the month, the distance between the comet and our planet will increase to 1.94 AU. For the next 20 years the comet will be moving toward the edge of the Solar System and will not return for another 26,000 years.

How to find C/2023 A3 (Tsuchinshan-ATLAS) in the sky?

You can spot C/2023 A3 (Tsuchinshan-ATLAS) with the Sky Tonight app. Open the app, and tap the magnifier icon at the bottom of the screen. Then type “C/2023 A3” and tap the target icon next to the corresponding search result. The app will show you the comet’s current position in the sky for your location. Point your device at the sky and follow the white arrow to find it. But keep in mind that C/2023 A3 (Tsuchinshan-ATLAS) won’t become a notable object until July 2024.

C/2023 A3 (Tsuchinshan-ATLAS) via Sky Tonight app.
C/2023 A3 (Tsuchinshan-ATLAS) via Sky Tonight app.

Will C/2023 A3 (Tsuchinshan-ATLAS) become the next great comet?

C/2023 A3 (Tsuchinshan-ATLAS) may well be the next great comet. Although there is no official definition of the term, great comets are usually exceptionally bright. So bright, in fact, that even a casual observer who isn't intentionally looking for a comet will notice it. Such comets also become well-known outside the astronomical community. The comets Hale-Bopp in 1997 and McNaught in 2007 were among the last comets to be called great. Again, comets are very unpredictable bodies, and there is always room for a surprise. For now, all we have to do is wait patiently for C/2023 A3's performance in 2024.

Bottom line

The comet C/2023 A3 (Tsuchinshan-ATLAS) has great potential and may become visible to the naked eye by October 2024. According to some forecasts, it could reach 0 magnitude or brighter. For now, it is only visible through a big telescope. Use the Sky Tonight app to locate C/2023 A3 (Tsuchinshan-ATLAS) in the sky. The app's Time Machine feature will allow you to see the comet's position in your sky in the future. Watch our video tutorial and learn how to use this feature.