21P/Giacobini–Zinner
Comet Giacobini–Zinner photographed from Moscow, Russia on 9 September 2018. | |
| Discovery | |
|---|---|
| Discovered by | Michel Giacobini Ernst Zinner |
| Discovery date | 20 December 1900 23 October 1913 |
| Designations | |
| P/1900 Y1 P/1913 U1 | |
| 1900 III; 1913 V; 1926 VI; 1933 III; 1940 I; 1946 V; 1959 VIII; 1966 I; 1972 VI; 1979 III; 1985 XIII; 1992 IX | |
| Orbital characteristics[3] | |
| Epoch | 26 March 2025 (JD 2460760.5) |
| Observation arc | 4,922 days (13.48 years) |
| Number of observations | 7,387 |
| Aphelion | 5.97 AU |
| Perihelion | 1.009 AU |
| Semi-major axis | 3.49 AU |
| Eccentricity | 0.7111 |
| Orbital period | 6.525 years |
| Inclination | 32.05° |
| 195.3° | |
| Argument of periapsis | 172.9° |
| Last perihelion | 25 March 2025[1] |
| Next perihelion | 30 August 2031[2] |
| TJupiter | 2.465 |
| Earth MOID | 0.018 AU |
| Jupiter MOID | 0.248 AU |
| Physical characteristics[4][5] | |
| Dimensions | 2.0 km (1.2 mi) |
| 7.39±0.01 hours | |
| Comet total magnitude (M1) | 13.2 |
| Perihelion distance at different epochs[6] | |||||||
| Epoch | Perihelion (AU) | ||||||
|---|---|---|---|---|---|---|---|
| 1894 | 1.23 | ||||||
| 1900 | 0.93 | ||||||
| 1985 | 1.03 | ||||||
| 2031 | 1.07 | ||||||
| 2078 | 0.97 | ||||||
Comet Giacobini–Zinner (officially designated as 21P/Giacobini–Zinner) is a periodic comet in the Solar System. It was discovered by Michel Giacobini, who observed it in the constellation of Aquarius on 20 December 1900. It was recovered two orbits later by Ernst Zinner, while he was observing variable stars near Beta Scuti on 23 October 1913.
It will pass 0.364 AU (54.5 million km) from Jupiter on 14 February 2029,[4] then come to perihelion on 30 August 2031 at 1.07 AU from the Sun,[2] and then pass 0.554 AU (82.9 million km) from Earth on 3 September 2031.[7]
Physical properties
The comet nucleus is estimated to be 2.0 km (1.2 mi) in diameter.[4] During its apparitions, Giacobini–Zinner can reach about the 7-8th magnitude,[8] but in 1946 it underwent a series of outbursts that made it as bright as 5th magnitude. It is the parent body of the Giacobinids meteor shower (also known as the Draconids). The comet currently has a minimum orbit intersection distance to Earth of 0.035 AU (5.2 million km).[4]
During the apparition of 2018, the optical spectra have revealed the comet is depleted in carbon-chain molecules and carbon dioxide, likely indicating its origin in relatively warm portion of the Solar System.[9]
Exploration
Giacobini–Zinner was the target of the International Cometary Explorer spacecraft, which passed through its plasma tail at a distance of 7,800 km (4,800 mi) on 11 September 1985, becoming the first comet ever visited in space exploration.[10] Earlier in the same month the comet was observed by the Pioneer Venus Orbiter.[11] In addition, Japanese space officials considered redirecting the Sakigake interplanetary probe toward a 1998 encounter with Giacobini–Zinner, but that probe lacked the propellant for the necessary maneuvers and the project was abandoned.
2025 Perihelion
21P/Giacobini-Zinner most recently passed perihelion on 25 March 2025. Closest Earth approach was 4 days before, on 21 March on the opposite side of the Sun at an unfavorable distance of 2.0 AU. It brightened to magnitude ~11.[12]
References
- ^ S. Yoshida. "21P/Giacobini–Zinner". www.aerith.net. Retrieved 5 January 2025.
- ^ a b "Horizons Batch for 21P/Giacobini-Zinner (90000323) on 2031-Aug-30" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Archived from the original on 2025-09-26. Retrieved 2025-09-26. (JPL#K253/3 Soln.date: 2024-Dec-05)
- ^ "21P/Giacobini-Zinner". Minor Planet Center. Retrieved 2025-10-30.
- ^ a b c d "21P/Giacobini–Zinner – JPL Small-Body Database Lookup". ssd.jpl.nasa.gov. Jet Propulsion Laboratory. Retrieved 10 January 2016.
- ^ M. M. Knight; R. Kokotanekova; N. H. Samarasinha (2023). "Physical and Surface Properties of Comet Nuclei from Remote Observations". arXiv:2304.09309 [astro-ph.EP].
- ^ Kinoshita, Kazuo (2019-05-23). "21P/Giacobini-Zinner past, present and future orbital elements". Comet Orbit. Retrieved 2025-10-30.
- ^ "Earth approach on 3 September 2031". JPL Horizons. Retrieved 2025-10-30.
- ^ B. King (29 August 2018). "Comet 21P/Giacobini-Zinner Shines in September". Sky & Telescope. Retrieved 15 September 2018.
- ^ Y. Shinnaka; H. Kawakita; A. Tajitsu (2020). "High-resolution Optical Spectroscopic Observations of Comet 21P/Giacobini–Zinner in its 2018 Apparition". Astronomical Journal. 159 (5): 203. arXiv:2004.11008. Bibcode:2020AJ....159..203S. doi:10.3847/1538-3881/ab7d34.
- ^ C. Stelzried; L. Efron; J. Ellis (1986). Halley Comet Missions (PDF) (Report). NASA. pp. 241–242. TDA Progress Report 42-87. This article incorporates text from this source, which is in the public domain.
- ^ P. Ulivi; D. M. Harland (2007). Robotic Exploration of the Solar System Part I: The Golden Age 1957–1982. Springer. p. 281. Bibcode:2007ress.book.....U. doi:10.1007/978-0-387-73983-0. ISBN 978-0-387-49326-8. ISSN 2945-7475.
- ^ G. van Buitenen. "21P/Giacobini–Zinner". astro.vanbuitenen.nl. Retrieved 8 November 2024.
External links
- 21P/Giacobini–Zinner at the JPL Small-Body Database
- 21P at Kronk's Cometography
- Comet 21P – Comet Watch