Ikeya-Seki (1965)

Comet Ikeya-Seki (C/1965 S1-A)

Comet Ikeya-Seki, formally designated C/1965 S1, was a stunning sungrazing comet that put on quite a show in 1965! It was one of the brightest comets of the 20th century and is a member of the Kreutz sungrazers, a family of comets believed to have originated from a larger comet that broke apart long ago. As a Kreutz sungrazer, it provided valuable information about these comets and their origins.

Key dates and information:

• September 18, 1965: Kaoru Ikeya and Tsutomu Seki, two amateur astronomers in Japan, independently discovered the comet. It was initially a faint telescopic object.

• October 21, 1965: Ikeya-Seki reached perihelion, its closest point to the Sun. It passed incredibly close, a mere 450,000 km (280,000 mi) above the Sun's surface! This made it briefly visible in daylight. The intense heat caused the comet's nucleus to fragment into at least three pieces. The breakup of its nucleus offered scientists a rare opportunity to study the composition and behavior of comets.

• Late October - November 1965: After perihelion, Ikeya-Seki developed a spectacularly long tail, stretching across the sky for millions of miles. It was a breathtaking sight for observers.

• Post-1965: The comet faded from view as it moved away from the Sun. Though it's still out there, with an orbital period estimated to be roughly 880 years, we won't see it again for a very long time. It will be roughly 440 years until the comet reaches aphelion. So roughly the year 2405. 

• Wikipedia article

• Britannica article

• Space.com article

• Cometography.com article

• Google images

Paloma's Orrery Plots:

• Comet Ikeya-Seki animated 120 days from 9-20-1965 (Very Large File: 89.1 MB)

  • Plot of Ikeya-Seki from 9-20-1965 (Very Large File: 93 MB)

  • Comet Ikeya-Seki animated 144 hours through perihelion from 10-18-1965 (Very Large File: 139.9 MB)

  • Comet Ikeya-Seki animated 48 hours through perihelion from 10-20-1965 (Very Large File: 139.9 MB)

  • Comet Ikeya-Seki full orbit from 3-15-2025 (Very Large File: 178.5 MB)