Comet Tsuchinshan-ATLAS observed with naked eye from Japan’s capital sphere

Comet Tsuchinshan-ATLAS, which has arrived from the edge of the solar system, was observed from various parts of Japan including the capital sphere on Oct. 13.

The faint comet with a white tail stretching upward was clearly visible with the naked eye in the low western sky after dusk in Tsukuba, Ibaraki Prefecture, and from Tateyama at the southern tip of Chiba Prefecture’s Boso Peninsula. It is said no comet has been so clearly visible to the naked eye in Japan since Comet Hale-Bopp in 1997.

Comet Tsuchinshan-ATLAS was discovered in 2023 by groups including the Purple Mountain Observatory in China and is believed to have come from the “Oort cloud,” an area of numerous small celestial bodies surrounding the outer solar system. The comet passed perihelion, the closest point in its orbit to the sun, on Sept. 28 and made its closest approach to Earth on Oct. 13.

According to the National Astronomical Observatory of Japan, the brightness of the comet is expected to be about magnitude 1.5 to 3 until around Oct. 15. It will then gradually fade but is expected to be observable at relatively easy-to-see altitudes in the western sky after dusk until around the end of October. After that, it will leave the solar system and apparently never return.

At their core, comets consist mostly of ice, with a small amount of gas and dust. When a comet’s orbit changes for some reason and it approaches the sun, the ice on its surface evaporates, and the released gas and dust form a tail, which can be observed from Earth.

(Japanese original by Koichiro Tezuka, Photo Group, and Shuichi Abe, Lifestyle, Science & Environment News Department; video by Naoki Watanabe, Photo Group)