C/1973 E1 (Kohoutek)
A comet hyped as the century's brightest that fell far short.
C/1973 E1 (Kohoutek) is a long-period comet discovered by Czech astronomer Luboš Kohoutek on 18 March 1973. It gained widespread public attention after early predictions suggested it could become one of the brightest comets of the 20th century, earning the moniker 'Comet of the Century,' but ultimately appeared far dimmer than projected, peaking at magnitude −3 and becoming synonymous with spectacular disappointment.
Quick Facts
- Discovery Ref
- NYT-19740107
- Discoverer
- Luboš Kohoutek
- Discovery Date
- 18 March 1973
- Designations
- 1973f, 1973 XIIICQ1
- Orbit Ref
- Horizons · JPL1 · MPC1
- Epoch
- 24 December 1973 (JD 2442040.5)
- Observation Arc
- 1.24 years (453 days)
- Earliest Precovery Date
- 28 January 1973
- Obs
- 812
- Perihelion
- 0.142 AU
- Aphelion
- 98,000 AU (inbound) / 3,700 AU (outbound)
- Eccentricity
- 0.999997 (inbound) / 0.99992 (outbound)
Facts from the source article.
Lore & Background
Comet Kohoutek was discovered serendipitously while Luboš Kohoutek was searching for Biela's Comet. He reviewed twice-exposed photographic plates taken on 7 and 9 March 1973 with the 80 cm Schmidt camera at Hamburg Observatory; the object appeared diffuse with central condensation at magnitude 15.5–16 in Hydra. At discovery it was 4.7 AU from the Sun and 4.0 AU from Earth, farther out than any previously discovered comet. Orbital calculations by Brian G. Marsden indicated a nearly parabolic orbit with eccentricity between 0.9999 and 1 and inclination 14.3°, bringing the comet to perihelion on 28 December 1973 at only 0.14 AU from the Sun. The comet may have originated from the early Solar System or another planetary system, with an initial orbital period possibly of several million years or this being its first inner-Solar-System passage. Its nucleus has an estimated average radius of 2.1 km.
Reader's Guide
Despite its underwhelming brightness, Kohoutek became the most well-studied comet of its time due to its early detection and unique characteristics. Numerous scientific assets were dedicated to observing it during its 1973–1974 traversal, leading to significant advances in cometary science. The identification of larger and more complex molecules alongside simpler chemical species confirmed that comets are composed of larger molecules that dissociate into simpler products. The detection of water, methyl cyanide, hydrogen cyanide, and silicon in Kohoutek marked the first time such species were observed in any comet. The significant presence of gases and plasma supported the 'dirty snowball' hypothesis of comet nuclei composition. Its disappointing display challenged longstanding assumptions about the light curves of comets entering the inner Solar System. Kohoutek's highly eccentric orbit suggests it may have formed early in Solar System formation or originated from another planetary system; its orbital period may have been initially several million years, or its 1973 apparition may have been its first trek inward. The comet is not expected to return for about 75,000 years.
Did You Know?
- Kohoutek was discovered farther from the Sun than any previous comet.
- It was the first comet in which water, methyl cyanide, hydrogen cyanide, and silicon were detected.
- The comet's peak apparent magnitude of −3 was far dimmer than the predicted −10.
More in Named Comets, Part 4 1-24
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