Key Takeaways:
- Comet Ikeya-Seki, discovered independently by Kaoru Ikeya and Tsutomu Seki in September 1965, was classified as a sungrazer comet.
- The comet's perihelion, its closest approach to the Sun, occurred on October 21, 1965, at a distance of approximately 290,000 miles (467,000 kilometers) above the Sun's surface.
- Ikeya-Seki achieved an exceptionally high brightness, reaching an estimated magnitude of –10.
- This magnitude signified that the comet's brightness was approximately 10% that of a full moon, significantly surpassing Venus's maximum brightness.
On Sept. 18, 1965, amateur astronomer Kaoru Ikeya and professional astronomer Tsutomu Seki each independently discovered what became the greatest comet of the century, Ikeya-Seki. When researchers calculated its orbit, they found it was a sungrazer — a comet that passes extremely close to the Sun. Small sungrazers usually evaporate or are torn apart by tidal forces. Large ones, however, can not only survive, but might also become extremely bright. Observers hoped Ikeya-Seki would fall into the latter category.
They didn’t have long to wait. The comet reached perihelion (its closest point to the Sun) Oct. 21, when it was just 290,000 miles (467,000 kilometers) above our daytime star’s surface. At its brightest, the comet reached an astounding magnitude –10, meaning that it shone about 10 percent as bright as the Full Moon, or 110 times brighter than Venus ever gets.
