In mid-October, Comet C/2023 A3 (Tsuchinshan-ATLAS) will pass close to Earth, promising to be one of the most exciting celestial events of the year. What makes it even more remarkable is that researchers predict the comet will be visible to the naked eye. But where and when should we look up in the sky, and why is it significant for space exploration the comet is passing between the Sun and Earth? We asked Krisztián Sárneczky, project coordinator at the HUN-REN Research Centre for Astronomy and Earth Sciences, for his insights.
Comet C/2023 A3 (Tsuchinshan-ATLAS) is a newly discovered comet, first observed in early 2023 at the Purple Mountain Observatory in China and later confirmed by the US-led ATLAS project. Based on its orbit, the comet reached its closest point to the Sun in September 2024, when it was visible to the naked eye from the Southern Hemisphere. Although it is now receding, experts believe its brightness could remain high in the second half of October, promising a spectacular celestial display.
Although the most spectacular view occurred around 9-10 October, when it was visible in the daytime sky, it will be observable in the twilight sky and later in the night sky over the coming days and weeks. According to astronomers, 14-15 October will be the first day to look for the comet in the twilight sky.
Comet C/2023 A3 (Tsuchinshan-ATLAS) will be visible to the naked eye about 1 to 1.5 hours after sunset, under the following conditions: a clear view of the western horizon and low light pollution.
At sunset, sharp-eyed observers will be able to spot a yellowish, teardrop-shaped tail in the western sky. The Svábhegy Observatory has announced several public events to coincide with the comet's arrival on 17 and 18 October. Comet C/2023 A3 will be the star of the evening, with participants able to observe its long, bright tail and nucleus.
Not only beautiful, but also important
"Comets like this are particularly interesting to astronomers because of their unique orbits. Comet C/2023 A3 will pass directly between the Sun and Earth, with the Sun favourably illuminating the dust particles released and left behind by the comet as it passes," explains Krisztián Sárneczky. "This will give astronomers a more accurate picture of the types of dust particles ejected by such a comet."
As similar comets often cross the paths of both Earth and the Moon, this phenomenon can tell researchers not only the size of the dust particles ejected but also their density. 'This could make it easier in the future to calculate the potential danger of such encounters for a possible mission to the Moon or Mars,' adds the astronomer.