| C/1980 E1 (Bowell) | |
| Discoverer: | Edward L. G. Bowell |
| Discovery Date: | 11 February 1980 |
| Epoch: | 3 January 1982 (JD 2444972.5) |
| Observation Arc: | 6.88 years |
| Obs: | 187 |
| Aphelion: | ~75,000 AU (inbound) |
| Perihelion: | 3.3639 AU |
| Eccentricity: | 1.057(hyperbolic trajectory) 1.053 (epoch 1984+) |
| Period: | ~7.1 million years (epoch 1950) Ejection (epoch 1977+) |
| Inclination: | 1.6617° |
| Asc Node: | 114.558° |
| Arg Peri: | 135.083° |
| Last P: | 12 March 1982 |
| M1: | 5.8 |
| Dimensions: | > 1 km |
C/1980 E1 is a non-periodic comet discovered by Edward L. G. Bowell on 11 February 1980 and which came closest to the Sun (perihelion) in March 1982. It is leaving the Solar System on a hyperbolic trajectory due to a close approach to Jupiter. In the 43 years since its discovery only two objects with higher eccentricities have been identified, 1I/ʻOumuamua (1.2) and 2I/Borisov (3.35).[1] [2]
Before entering the inner Solar System for a 1982 perihelion passage, C/1980 E1 had a barycentric (epoch 1950-Jan-01) orbit with an aphelion of 75000AU, and a period of approximately 7.1 million years.
As the comet was approaching on 9 December 1980, it passed within 0.228 AU of Jupiter, which accelerated the comet briefly giving an (epoch 1981-Jan-09) eccentricity of 1.066. The comet came to perihelion on 12 March 1982, when it had a velocity of 23.3km/s with respect to the Sun. Since the epoch of 1977-Mar-04, C/1980 E1 has had a barycentric eccentricity greater than 1, keeping it on a hyperbolic trajectory that will eject it from the Solar System. Objects in hyperbolic orbits have a negative semimajor axis, giving them a positive orbital energy. After leaving the Solar System, C/1980 E1 will have an interstellar velocity of 3.77 km/s. The Minor Planet Center does not directly list a semimajor axis for this comet. On 24 January 2022, C/2024 L5 (ATLAS) had a similar episode with Saturn, resulting in its ejection from the Solar System.
The escape velocity from the Sun at Neptune's orbit is 7.7 km/s. By June 1995, the comet was passing Neptune's orbit at 30.1 AU from the Sun continuing its ejection trajectory at 8.6 km/s. Since February 2008, the comet has been more than 50 AU from the Sun.
| 1682-03-12 | 248.8AU | 2.68 | ± 7 million km | |
| Perihelion | 3.364AU | 23.3 | ± 1589 km | |
| 2282-03-12 | 337.2AU | 4.43 | ± 5 million km |
Emission of OH (hydroxide) was observed pre-perihelion while the comet was nearly 5 AU from the Sun. CN (cyanide) was not detected until the comet was near perihelion. The comet nucleus was estimated to have a radius of several kilometers. The surface crust was probably a few meters thick.