Comet Ikeya–Seki

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There are two comets named Ikeya–Seki: C/1965 S1 (this one), and C/1967 Y1, a.k.a. 1968 I, 1967n.
C/1965 S1 (Ikeya–Seki)
Semi-major axis
91.6 AU (A)
103.7 (B) AU
Eccentricity0.999915 (A)
0.999925 (B)
Orbital period795 years (epoch 2200 for A)[2]
946 years (epoch 2200 for B)[3]
Inclination141.8642° (A)
141.861° (B)
Last perihelionOctober 21, 1965[1]

Comet Ikeya–Seki,

long-period comet discovered independently by Kaoru Ikeya and Tsutomu Seki. First observed as a faint telescopic object on September 18, 1965, the first calculations of its orbit suggested that on October 21, it would pass just 450,000 km (280,000 mi) above the Sun
's surface, and would probably become extremely bright.

Comets can defy such predictions, but Ikeya–Seki performed as expected. As it approached

Great Comet
of 1965.

The comet was seen to break into three pieces just before its perihelion passage. The three pieces continued in almost identical orbits, and the comet re-appeared in the morning sky in late October, showing a very bright tail. By early 1966, it had faded from view as it receded into the outer Solar System.

Ikeya–Seki is a member of the

a large comet which broke up in 1106
.

Discovery and observational history

Black-and-white photograph of a crowd observing the comet
Onlookers in Amsterdam awaiting the comet's apparition on 21 October 1965

Comet Ikeya–Seki was independently discovered on 18 September 1965 by Japanese amateur astronomers

full Moon. The comet also projected a slightly curved tail; 2° of the tail was sufficiently visible to the naked eye with manual obscuration of the Sun.[7]

Ikeya–Seki reached perihelion at 21:18 

reflector telescope at the United States Naval Observatory Flagstaff Station in mid-March 1966.[10]

Structure and composition

A 6-minute exposure of Ikeya–Seki's nucleus on 6 November 1965, faintly resolving the two primary components of the comet's fractured nucleus

Observations obtained by the

K around perihelion.[11]

Observing campaigns

Ikeya–Seki's perihelion presented a unique opportunity for astrophysical observations to be taken of a bright comet passing extremely close to the Sun.

radio emission from the comet yielded negative results. A Convair 990 operated by NASA out of Hawaii and a Boeing 707 with scientists from Los Alamos National Laboratory were also involved in observational efforts targeting Ikeya–Seki. Gemini 6A was also planned to incorporate observation of the comet until the loss of the Agena target vehicle led to the cancellation of the original mission. Elizabeth Roemer remarked of the breadth of observational data in Publications of the Astronomical Society of the Pacific that "There seems no doubt that the appearance of Comet Ikeya–Seki will stand as a landmark in cometary physics."[9]

Gallery

  • Comet Ikeya–Seki, seen from Canberra, 31 October 1965. Drawing by David Nicholls.
    Comet Ikeya–Seki, seen from Canberra, 31 October 1965. Drawing by David Nicholls.
  • Comet Ikeya–Seki, 30 October 1965. Photo by James W. Young (TMO/JPL/NASA)
    Comet Ikeya–Seki, 30 October 1965. Photo by
    James W. Young (TMO
    /JPL/NASA)

Notes

  1. visible light
    . A more negative value for apparent magnitude indicates a brighter object.

References

  1. ^ a b "JPL Small-Body Database: C/1965 S1-A (Ikeya-Seki)". Jet Propulsion Laboratory. Retrieved 26 August 2023.
  2. barycenter
    (Sun+Jupiter). Select Ephemeris Type:Elements and Center:@0)
  3. barycenter
    (Sun+Jupiter). Select Ephemeris Type:Elements and Center:@0)
  4. ^ "Brightest comets seen since 1935". International Comet Quarterly. Archived from the original on 28 December 2011. Retrieved 12 October 2023.
  5. ^ a b c d e f g h i j Hale, Alan (24 October 2020). "Comet of the Week: Ikeya-Seki 1965F". RocketSTEM. RocketSTEM Media Foundation. Retrieved 15 May 2023.
  6. ^
    JSTOR 40674261
    .
  7. ^
    JSTOR 40674283
    .
  8. Bibcode:1965PASJ...17..433H
    .
  9. ^
    JSTOR 40674308
    .
  10. ^
    JSTOR 40674376
    .
  11. doi:10.1086/110884
    .

External links

Media related to Comet Ikeya-Seki at Wikimedia Commons

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