Comet C/2023 A3 (Tsuchinshan-ATLAS)

Comet C/2023 A3 (Tsuchinshan-ATLAS) at the upper right of the image along with the Milky Way.
20 sec. exposure, ISO 5000, f3.5
OM1-MarkII, 18mm
Considered a long-period comet, Comet C/2023 A3—also known as Comet Tsuchinshan-ATLAS or Comet Purple Mountain-ATLAS—recently made its closest approach to the Sun, after having traveled from the Oort Cloud. It’s forecasted to be brightest on October 9 around magnitude -3, and around magnitude +2 on October 12 when the comet is at its closest point to Earth.
Where Did C/2023 A3 Come From?
Comets get the designation long-period if their orbits are more than 200 years long; C/2023 A3’s orbit is at least 80,000 years long. It most likely came from a region called the Oort Cloud, which is a spherical volume surrounding the planets that may have formed early on in our solar system’s history when icy objects were flung outward away from the Sun due to the gravitational action of the planets.

How Was This Comet Named?

Each part of a comet’s name has a purpose! It helps us identify what kind of comet it is, when it was discovered, and where it was discovered.

Comet C/2023 A3 (Tsuchinshan-ATLAS)’s name can be broken down like this:

C/ means that this comet is classified as a non-periodic comet, which is the designation for comets that don’t have a regular orbit around the Sun or comets whose orbits are more than 200 years long
2023 identifies the year this comet was discovered
A3 tells us the time period of the year that this comet was discovered with an alphabetic letter and a number to signify how many other comets were discovered in this time period
A = the first half of January, B = the second half of January, and so on and so forth, except the letter I and Z are never used
Tsuchinshan-ATLAS = the names of the two observatories that jointly get credit for discovering the comet. Pronunciation: [zz-jing-shan]-ATLAS. Transliteration: Purple Mountain [Observatory]-ATLAS.