C/1964 N1 (Ikeya)
Long-period comet discovered by Kaoru Ikeya in 1964.
C/1964 N1 (Ikeya), designated Comet 1964f, is a long-period comet found by Japanese amateur Kaoru Ikeya on 3 July 1964. It was his second comet discovery, following C/1963 A1. At the time, it was in the morning sky within the constellation Taurus, near the Hyades star cluster, with an estimated magnitude of 8, and it was moving southeast.
The comet brightened through July. On 19 July, Jim Young at Table Mountain Observatory spotted it without optical aid. It reached perihelion on 1 August 1964, achieving an apparent magnitude of 2.7. By 6 August, it remained naked-eye visible as it passed within 1–2° of the star Rigel, though it then became hard to observe in the morning twilight. Its closest approach to Earth came on 12 August, at roughly 0.2 AU (30 million km) and a solar elongation of 31°. On 15 August, S. Archer in Australia reported a magnitude of 2.8 and a tail extending 4.5 degrees. By late August, the comet appeared in the northern hemisphere’s evening sky, low near the horizon and noticeably fainter. On 2 September, its magnitude was estimated at 6.5; by 12 September, it had faded to 8.5. The final detection occurred on 7 October 1964, at magnitude 10.4.
Spectroscopic observations on 29 and 30 July at Mount Wilson Observatory revealed C₂, C₃, CH, and CN in the comet’s spectrum. Photoelectric measurements in the coma near the nucleus gave N(CH)/N(CN) and N(C₃)/N(CN) ratios both around 0.3.
The comet is thought to be the parent body of several meteor showers. Models indicate it produces four streams intersecting Earth’s orbit. The first linked shower is the July ξ Arietids. It is also considered the source of the ϵ-Geminids and possibly the ξ-Geminids. All these showers are diffuse and sparse.
Quick Facts
- Discoverer
- Kaoru Ikeya
- Discovery Date
- 3 July 1964
- Designations
- 1964f
- Epoch
- 1964-Jul-28.0
- Observation Arc
- 56 days
- Obs
- 36
- Aphelion
- 110.97 AU
- Perihelion
- 0.822 AU
- Semimajor
- 55.90 AU
- Eccentricity
- 0.9853
- Period
- 418 years
- Inclination
- 171.92°
Facts from the source article.
Lore & Background
The comet was discovered by Japanese amateur astronomer Kaoru Ikeya on 3 July 1964, his second comet discovery after C/1963 A1. At discovery it was in the morning sky in the constellation Taurus, near the Hyades star cluster, with an estimated magnitude of 8 and moving southeast. It brightened through July and was first observed with the naked eye on 19 July by Jim Young at Table Mountain Observatory. After perihelion on 1 August, it was visible to the naked eye on 6 August as it passed 1–2° from Rigel, then became difficult to observe in morning twilight. Its closest approach to Earth was on 12 August at about 0.2 AU and a solar elongation of 31°. On 15 August, S. Archer in Australia reported a magnitude of 2.8 and a tail 4.5 degrees long. The comet became visible from the northern hemisphere in the evening sky in late August, low near the horizon and faded noticeably. By 2 September its magnitude was 6.5, by 12 September it was 8.5, and it was last detected on 7 October 1964 at magnitude 10.4.
Reader's Guide
C/1964 N1 (Ikeya) holds significance as a long-period comet that reached naked-eye brightness and was studied spectroscopically. Its spectrum, obtained on 29 and 30 July 1964 by Mount Wilson Observatory, revealed the presence of C2, C3, CH, and CN, with photoelectric measurements yielding relative abundances: N(CH)/N(CN) and N(C3)/N(CN) both about 0.3 in the coma near the nucleus. The comet is considered the parent body of several meteor showers, including the July ξ Arietids and the ϵ-Geminids, and possibly the ξ-Geminids, though all these showers are diffuse and have few meteors. Its legacy includes being the second comet discovered by Kaoru Ikeya and providing data on cometary composition and meteor stream origins.
Did You Know?
- It reached an apparent magnitude of 2.7 at perihelion on 1 August 1964.
- It is considered the parent body of the July ξ Arietids and ϵ-Geminids meteor showers.
Frequently Asked Questions
Who discovered C/1964 N1 (Ikeya) and when?
Japanese amateur astronomer Kaoru Ikeya spotted this long-period comet in the morning sky near the Hyades cluster in Taurus on 3 July 1964. It was his second confirmed comet find, coming after C/1963 A1.
How close did C/1964 N1 (Ikeya) get to Earth and when?
The comet reached perihelion on 1 August 1964 and then passed its nearest point to our planet on 12 August at roughly 0.2 AU. At that distance it was still easily visible to the naked eye.
What was the peak brightness of C/1964 N1 (Ikeya)?
At perihelion the comet shone at an apparent magnitude of about 2.7, well within naked-eye range. Even before perihelion, on 19 July, Jim Young at Table Mountain Observatory was able to pick it out without any optical aid.
What happened to C/1964 N1 (Ikeya) after it faded from view?
Its last recorded observation came on 7 October 1964, when it had dimmed to magnitude 10.4. As a long-period comet, it then continued outward on its extended orbit, leaving the inner solar system for decades to come.
Why is C/1964 N1 (Ikeya) remembered in amateur astronomy circles?
It proved that a dedicated backyard observer could still turn up a bright, naked-eye comet in the mid-1960s, cementing Ikeya's reputation as a prolific discoverer. Its designation as Comet 1964f and its summer-1964 visibility made it a standout event for skywatchers of that era.
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