In astronomical terms, the protagonist of the year is the comet 3I/ATLAS. It was discovered on July 1 and since then it has been the subject of numerous observations with all types of instruments, both located in the Land as in space and even on planets as far away as Marsstudies by astronomers and conjectures, some as extravagant and lacking scientific basis – and common sense – as that it could be an alien spacecraft.
The reason for so much interest is that 3I/ATLAS It is not a comet like any other of ours Solar system. Its origin, unknown, comes from outside it and its age has been estimated at more than 7 billion years. That is, some 2.5 billion years older than the Solar System itself which is now crossing. The information it can offer to understand what lies beyond the limits of our planetary system is invaluable.
Now, after seeing it in the headlines so many times, you may have wondered where the name 3I/ATLAS came from for this interstellar comet. It is not coincidental, but obeys the system with which celestial bodies are named.
The official name of comets is decided by the International Astronomical Union (IAU) through your Minor Planet Center (MPC)who manages all discoveries and assigns names and designations.
Provisional designation
First, a provisional designation is made with a code that includes the following concepts:
- Year of discovery.
- Fortnight of the month in which it has been detected. Each month has two astronomical fortnights, so that A and B are the two fortnights of the month of January and X and Y are those of December. In between, almost the entire alphabet to cover the rest of the months of the year. There may also be a second letter, in the case of the famous 2024 YR4something that applies to asteroids, but not to comets, in which only one letter is used for the fortnight. In this case, the secondary letter –R- It is part of the code that indicates the sequential order of discovery within that fortnight, indicated by the AND.
- Order number within that fortnight. Each discovery within the same fortnight receives a consecutive number indicating how many objects have been detected before in that interval. In 2024 YR4, the suffix R4 It indicates its specific position within the total sequence of discoveries made in that fortnight. All this terminology does not refer only to comets, but also includes asteroids, objects with a cometary appearance that are still unconfirmed and NEOacronym in English for Near Earth Objecta category that includes both asteroids and comets.
Another example of a provisional comet designation is C/2023 A3. and that c initial corresponds to the type of object:
- C/ → Non-periodic comet
- P/ → Periodic comet
- D/ → Comet that has disintegrated
- YO/ → Interstellar object (such as 1I/ʻOumuamua either 3I/ATLAS)
After the provisional designation made by the MPC, the name of the discoverer is added. This can be a person, a team or an observatory. If there are several discoverers, all are included.
So, C/2023 A3 becomes C/2023 A3 (Tsuchinshan–ATLAS)being Tsuchinshan the international name of Purple Mountain Observatory in China and ATLAS that of the American Asteroid Terrestrial-impact Last Alert System (Asteroid Terrestrial Impact Early Warning System) that operates various telescopes located on the island of Hawaii, South Africa and Chili. In the case of C/2023 A3 They both appear as discoverers because they both did it independently in the same period of time.
Permanent appointment
Finally, when a comet repeats perihelion – closest approach to the Sun – and is confirmed to be periodic, it also receives a sequential number. It is the case of 1P/Halley either 2P/Encke. These are already definitive names, so they do not indicate the year of discovery, which is only used in the provisional one; therefore, 1P/Halley is not 1P/1682 Halley.
Thus, the permanent designation consists only of the sequential number, the letter of the comet type and the name of the discoverer.
What does 3I/ATLAS mean?
Under these rules, the name it has received is perfectly understood 3I/ATLAS. He 3 It is because it is the third interstellar object that has been discovered, after 1I/ʻOumuamua in 2017 and 2I/Borisov in 2019.
The Yo corresponds to its classification as an interstellar object that comes from beyond the Solar System and ATLAS to the aforementioned observation system to which the IAU attributed the discovery.