In recent years, the number of comets has increased, mainly due to advances in science and technology and various astronomical equipment that automatically detect new objects 24 hours a day. For example, 73 comets were discovered last year in 2020, compared to 66 in 2019 the year before, and an average of 6 new comets were found every month.
Comet: Images from the Internet
Once a new comet is observed and confirmed multiple times, it is assigned a temporary (tentative) name (code name). For example, what do the letters and numbers in the name of the C/2020 F3 (NEOWISE) comet that caught fire last summer mean?
Let's first talk about what the first letter means, because the first letter is important and it already distinguishes the basic characteristics of the comet. Common letters are generally C/, P/, I/, D/, A/, X/, of which C/ and P/ are the most common. Let's explain what each letter means:
P/ means that the comet is periodic, in other words its orbit is a closed ring (eccentricity less than 1) that will return to the inner solar system in the future, or has been confirmed to have returned and been successfully observed.
C/Comet is aperiodic, meaning its orbit is open (eccentricity greater than or equal to 1). Comets fly into the inner solar system only once, then walk away and never come back, or return after a very long, long period (more than 200 years).
Type I/ comet origin is from interstellar, to determine whether the comet is from interstellar to see its orbital characteristics, such as a significant eccentricity greater than 1 orbit, is a hyperbolic orbit. The first officially identified interstellar object was 1I/2017 U1 (Oumuamua), which has an eccentricity of about 1.2.
D/ indicates that a periodic comet has been observed before (at least once) and then gradually disappeared, so this type is called Disapear.
A/ This is used to indicate objects that were initially identified as possible comets, but further investigation confirmed their asteroid traits. This naming is often used when asteroids are discovered in comet-like orbits.
X/ indicates that the orbit of the comet cannot be determined (for example, a historical comet that cannot be accurately observed).
The second part of the name, the number immediately after the first type of letter, is the year the comet was discovered. For example, C/2020 F3 (Neowise) was discovered in 2020.
The next third digit is a combination of letters and numbers, the letters represent the month (divided into upper and lower half months), the letter A represents the first half of January, B represents the second half of January, C represents the first half of February, D represents the second half of February, and so on. The numbers behind it indicate that the comet was the first to be discovered in the half-moon where it was located. For example, F3 mentioned earlier means the third comet discovered in the second half of March.
The last part is a name, usually enclosed in parentheses. In order to honor the discoverer, it is usually named after the discoverer's last name (note that it is a surname, such as Michael Jordan using Jordan, Donald Trump using Trump), or using the unit of discovery, project, etc. (such as so-and-so sky survey project).
Example
Example of comet naming
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