Astronomers have reported a rare phenomenon: two comets will appear in the sky at once.

They can be observed with the naked eye one by one

Two comets will appear in the sky at once in October - this phenomenon is considered rare among representatives of the astronomical community. We are talking about comet C/2023 A3 (Zijinshan - ATLAS), discovered in January 2023, and about the circumsolar comet C/2024 S1 (ATLAS), spotted on September 27, 2024.

C/2023 A3 (Zijinshan - ATLAS) was discovered at the Chinese Zijinshan Observatory and a little later, in February, the “find” was confirmed by the ATLAS telescope in South Africa. The comet moves in a weakly hyperbolic orbit. This means that it will likely fly through the solar system just once, and we will never see it again. The comet has already passed perihelion (closest distance from the Sun) on September 27, and now we are waiting for its closest approach to the Earth. It will happen on October 12, 2024. The distance on this day between our planet and the comet will be about 70.6 million kilometers. However, due to its brightness, we can observe it with the naked eye. It is expected that Comet C/2023 A3 may be brighter than Comet C/2020 F3 (NEOWISE), which graced the sky four years ago.

The peculiarity of comet C/2023 A3 (Zijinshan - ATLAS) is that it has three tails. The main tail is dust, the second is blue, consisting of gas, and the third is secondary dust, consisting of large dust grains that the solar wind blows 45 degrees to the right of the main tail.

The maximum expected brightness of the comet is -2 magnitude (this is how we see Jupiter). According to the AstroAlert portal, it is possible that C/2023 A3 will become the brightest comet in the northern hemisphere in the last 27 years.

How to look for the bright comet C/2023 A3 (Zijinshan - ATLAS)

To do this, you will need the following conditions: an open western horizon without buildings, trees and hills, no clouds or haze. Even though the comet promises to be visible to the naked eye, at least have binoculars ready just in case.

Starting from October 12, it will be possible to “catch” the celestial wanderer at a low altitude above the western part of the horizon, where the Sun set 1 hour before. The point in the sky is between the star Arcturus and Venus. Against the background of bright twilight, the comet can be visible as a dot from 18.30 to 19.10 Moscow time.

Further, the size of the comet will gradually decrease, and the tail will gradually increase. By October 14, it may “stretch out” and become the size of the tail of the Big Dipper. You can watch this spectacle from 19.10.

By October 20-21, the comet will gradually cease to be visible to the naked eye. To admire it almost until the end of the month, you will need to prepare telescopes.

For those who do not have time to detect the first October comet in the sky, another will arrive to replace it. The new bright comet C/2024 S1 (ATLAS) was discovered in Hawaii on September 27 using the ATLAS system. The celestial body, according to scientists, belongs to the family of circumsolar Kreutz comets - comets that fly as close as possible to the Sun, risking being burned to the ground. There is an assumption that this family used to be one large comet, which collapsed in 1106. The new comet C/2024 S1 will pass perihelion on October 28 at a distance of only 500 thousand kilometers from the star (slightly more than the distance from the Earth to the Moon). On October 29, it will be separated from the Earth by 75 million kilometers.

It is possible that it will become even brighter than the previous comet C/2023 A3 - its brightness can reach from -5 to -7 magnitude. A celestial visitor with a long curved tail can be observed in the mornings after October 29. It will be so bright that it can be seen next to the Sun (to search, astronomers advise blocking it and examining the surrounding area).