This story originally appeared in WITH WIRE in Spanish and has been translated from Spanish.
C/2023 A3, also known as Tsuchinshan–ATLAS and considered “the comet of the century,” will appear in all its splendor in our sky during September and October 2024. Due to its characteristics, astronomers believe it will be exceptionally bright, similar to Halley’s Comet in 1986 or NEOWISE in 2020.
Comets like C/2023 A3 are balls of frozen gas, rock and dust that orbit the Sun. They are often spectacular because of two physical phenomena that occur during their journey.
The first is the tail, which extends from the nucleus of the comet as it approaches the star it orbits. Solar radiation from the star (in our case, the Sun) vaporizes some of the comet’s frozen material, ejecting gas and dust from the nucleus that then reflects the star’s light. As a comet approaches its star, its tail grows in size due to the increased solar radiation.
The second phenomenon is the comet’s coma, a sublimated ice envelope that forms a sort of atmosphere around the nucleus as it approaches its star, also due to solar radiation. This also increases the comet’s brightness.
What is the best day to see the comet?
C/2023 A3 will shine brightly in the northern hemisphere sky starting on September 27 and will remain visible until the last week of October. During this period, the comet will reach its minimum distance from the Sun, before beginning its return journey out of the solar system.
According to the specialist blog Cometography, the day on which C/2023 A3 will shine most brightly will be October 2. The comet’s tail will be long and spectacular at this point due to its proximity to the sun.
What time will the comet be visible?
Due to its proximity to the Sun, the comet will behave in a similar way to Mercury and Venus: it will be seen near the horizon, in the path of the Sun and just before sunrise. The best time to admire it will be between 5 and 7 a.m. starting on September 27. The timing and position will be similar throughout the Northern Hemisphere.
As October progresses, the comet will rise in position relative to the horizon and at the same time fade. As Tsuchinshan-ATLAS is a long-orbiting body from the Oort cloud, beyond the edge of the solar system, it will not appear in our skies again for tens of thousands of years.
