This story was originally Appear in wired spanish and has been translated from Spanish.
C/2023 A3, also known as Tsuchinshan-ATLAS, is considered the “comet of the century” and will appear in all its glory in our skies during September and October 2024. It will be unusually bright, similar to Halley’s Comet in 1986 or NEOWISE in 2020.
Comets like C/2023 A3 are spheres of frozen gas, rock and dust that orbit the sun. They are often spectacular due to two physical phenomena that occur during the journey.
The first is the comet’s tail, which extends from the comet’s core as the comet approaches the star it orbits. Solar radiation from the star (in our case, the Sun) vaporizes some of the comet’s frozen material, blowing gas and dust away from the comet’s core, which then reflects the star’s light. As a comet gets closer to its star, its tail grows larger due to increased solar radiation.
The second phenomenon is the coma of a comet. This is a envelope of sublimated ice that forms an atmosphere around the core as it approaches the star, again due to solar radiation. This also enhances the comet’s brightness.
What’s the best day to see the comet?
C/2023 A3 will shine in Northern Hemisphere skies starting on September 27 and will be visible until the last week of October. During this time, the comet will reach its minimum distance from the sun and then begin its return to the solar system.
According to the professional blog Cometography, the brightest day of C/2023 A3 will be October 2.
When is the comet visible?
Because of its proximity to the Sun, the comet will behave similarly to Mercury and Venus: it will be seen near the horizon, in the path of the Sun, just before sunrise. The best time to watch it is from 5 a.m. to 7 a.m. on September 27. Times and locations are similar throughout the Northern Hemisphere.
As October progresses, the comet’s position relative to the horizon will rise and its brightness will decrease. Because Chuqinshan-Atlas is a long-orbiting object and comes from the Oort cloud beyond the edge of the solar system, it won’t reappear in our skies for tens of thousands of years.
