#comet swan

2025 October 23

SWAN, Swan, Eagle

Image Credit & Copyright: Adam Block

Explanation: Comet C/2025 R2 (SWAN) sports a greenish coma and fainter tail, seen against congeries of stars and dusty interstellar clouds in this 7 degree wide telescopic field of view from October 17. On that date, the new visitor to the inner Solar System obligingly posed with two other celestial birds seen toward the center of our Milky Way. Messier 16, near the bottom of the frame, and Messier 17 are also known to deep skywatchers as the Eagle and the Swan nebulae. While the comet coma's greenish glow recorded in the image is due to diatomic carbon gas fluorescing in sunlight, reddish hues seen in the nebulae, star forming regions some 5,000 light-years distant, are characteristic of ionized hydrogen gas. Comet SWAN is outbound now but still a good comet for binoculars and small telescopes that can look close to the southern horizon in the northern hemisphere's early evening skies. C/2025 R2 (SWAN) was closest to our fair planet on October 20, a mere 2.2 light-minutes away.

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)

NASA Official: Amber Straughn

A service of: ASD at NASA / GSFC,

NASA Science Activation

First of all, we all know our ship name is Shiwang/史汪 from Shi Qiang and Wang Miao's names, and because it sounds quite similar to the English word "swan", there're some fans also calling the ship swan on weibo, especially when they don't want their posts to be searchable with Shiwang.

Comet C/2006 M4 (SWAN), were discovered in June 2006, and Liu Cixin's Three Body Problem first started to get published on a sci-fi magazine in May 2006. This comet is a non-period comet which means it only passes through the solar system once, and makes me think of Shi Qiang and Wang Miao only passed through each other's lives once in the book canon.

C/2020 F8 (SWAN), or Comet SWAN were discovered in May 2020, and Tencent's Three-Body started shooting in June 2020. This is an oort cloud comet which is the most long-period comet, and it takes more than 200 years for them to orbit around the sun. Does it remind you of Shi Qiang sleeping for 200 years?

These comets were named SWAN because their photos were taken by Solar Wind Anisotropies (SWAN), and the Chinese translation is 史汪, with exactly the same Chinese characters as the ship name. So they are called "史汪彗星".

Shiwang's story only lasted a month in canon, and it's interesting that the discovery date and the publishing/shooting date also had roughly a month in between them. And since comets are known to glow green and blue (in the case of the 2020 comet, it has a green comet head and a blue comet tail), somehow this series of Three-Body character posters have green and blue as the theme color for Shiwang (in this series of posters, 3/11 are blue, 2/11 are green) :

"A green comet likely is breaking apart and won’t be visible to the naked eye"