C/1980 E1 (Bowell)
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 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 3 objects with higher eccentricities have been identified, 1I/ʻOumuamua, 2I/Borisov, and 3I/ATLAS.
Overview
Before entering the inner Solar System for a 1982 perihelion passage, C/1980 E1 had a barycentric orbit with an aphelion of, 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 eccentricity of 1.066. The comet came to perihelion on 12 March 1982, when it had a velocity of 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.
| Date | Sun distance | Velocity wrt Sun | Uncertainty region |
| 1682-03-12 | 2.68 | ± 7 million km | |
| Perihelion | 23.3 | ± 1589 km | |
| 2282-03-12 | 4.43 | ± 5 million km |
Emission of OH was observed pre-perihelion while the comet was nearly 5 AU from the Sun. CN 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.