 Comet Tempel–Tuttle photographed by theHubble Space Telescope on 9 January 1998 | |
| Discovery | |
|---|---|
| Discovered by | Wilhelm Tempel Horace Parnell Tuttle |
| Discovery date | 19 December 1865 |
| Designations | |
| |
| 1699 II, 1866 I, 1965 IV | |
| Orbital characteristics[2][3] | |
| Epoch | 25 February 2023 (JD 2460000.5) |
| Observation arc | 631.69 years |
| Earliestprecovery date | 25 October 1366[1] |
| Number of observations | 471 |
| Aphelion | 19.732 AU |
| Perihelion | 0.975 AU |
| Semi-major axis | 10.354 AU |
| Eccentricity | 0.90587 |
| Orbital period | 33.318 years |
| Inclination | 162.48° |
| 235.41° | |
| Argument of periapsis | 172.45° |
| Mean anomaly | 271.09° |
| Last perihelion | 28 February 1998 |
| Next perihelion | 20 May 2031 |
| TJupiter | –0.637 |
| EarthMOID | 0.008 AU |
| Physical characteristics | |
Mean radius | 1.8 ± 0.2 km (1.12 ± 0.12 mi)[4][5] |
| 14.79–15.31 hours[6] | |
| Comet total magnitude (M1) | 10.0 |
| Comet nuclear magnitude (M2) | 16.0 |
55P/Tempel–Tuttle (commonly known asComet Tempel–Tuttle) is aretrogradeperiodiccomet with anorbital period of 33 years. It fits the classical definition of a Halley-type comet with aperiod of between 20 and 200 years. It was independently discovered byWilhelm Tempel on 19 December 1865, and byHorace Parnell Tuttle on 6 January 1866. It is the parent body of theLeonidmeteor shower.
In 1699, it was observed byGottfried Kirch,[9] however it was not recognized as aperiodic comet until the discoveries by Tempel and Tuttle during the 1866perihelion. In 1933, S. Kanda deduced that the comet of 1366 was Tempel–Tuttle, which was confirmed by Joachim Schubart in 1965.[10] On 26 October 1366, the comet passed 0.0229 AU (3.43 million km; 2.13 million mi) from Earth.[11] It is possible the comet was also observed in October 1234, however it is only mentioned briefly by a single Japanese source, and also a comet observed in China in January 1035 could be comet Temple–Tuttle, however unless it had undergone a major outburst, it would have been too dim to observe with the naked eye.[12]
Comet Tempel–Tuttle was recovered by J. Schubart in images taken by Michiel John Bester on 30 June 1965 using the 10-inch telescope ofBoyden Observatory, South Africa. At that time the comet had an apparent magnitude of 16.[13] The presence of the comet was confirmed in plates obtained byPalomar Observatory on 30 June. These were the only two observations of the comet during the 1965 apparition.[14]
The comet was recovered on 4 March 1997 by Karen Meech, Olivier Hainaut andJames "Gerbs" Bauer, at the University of Hawai`i. At the time it was very faint (22.5 mag), but the recovery proved that it was returning on schedule and that its orbit was very well determined.[15] During the 1998 apparition the comet brightened more than predicted and reached an apparent magnitude of 7.4–7.8 in late February and could be observed with binoculars. It was last observed on 5 July 1998.[16]
The nucleus of the comet was observed byHubble Space Telescope during the 1998 apparition, and assuming analbedo of 0.04, its nucleus was estimated to have a mean radius of 1.8 km.[17] Spectrometric observations of its nucleus reveal that it has a reddish color, with a B−V of0.75±0.05 and V−R of0.51±0.05.[7][8] A jet was observed emanating from the nucleus and based on its movement the rotation period was calculated to be between14.79±0.02 and15.31±0.03 hours.[6]
The spectrum of the comet revealed the presence ofdiatomic carbon, NH2 and [Oi]. The relative production rates indicate that the comet is depleted in diatomic carbon, with the gas-to-dust ratio also indicated it was gas rich compared withHalley's Comet.[18] Theinfraredspectrum of the comet closely resembled that of ablack body with a temperature of 330 K and lackedsilicate emission that has been detected in other comets.[19]
William Huggins observed the spectrum of the comet in January 1866, making it the second time spectrographic observations of a comet were obtained.[20]
55P/Tempel–Tuttle is estimated to have a total nuclear mass of 1.2×1013 kg,[21] with its meteoroid stream is estimated to have a mass of 5×1012 kg in total.[21]
| Year | Nominal geocentric distance (AU) |
|---|---|
| 1366 | 0.023 AU (3.4 million km)[11][16] |
| 1699 | 0.064 AU (9.6 million km)[22][16] |
| 1832 | 0.171 AU (25.6 million km)[23][22] |
| 1998 | 0.356 AU (53.3 million km)[24][22] |
| 2031 | 0.791 AU (118.3 million km)[25][22] |
| 2163 | 0.132 AU (19.7 million km)[2] |
Orbital calculations in 2014 suggested that Tempel–Tuttle was at one point about 5,000 years before discovery, the comet made a close encounter withUranus, which reduced its orbital period from that of a long-period comet out to theKuiper Belt to its present-day 33-year retrograde orbit around the Sun, however this remains unconfirmed.[26]
The comet currently has an Earth-MOID of about 0.008 AU (1.2 million km).[2]
Tempel–Tuttle is the parent body of theLeonid meteor shower. The retrograde orbit of 55P/Tempel–Tuttle causes meteors to impact Earth at a high speed of 70 km/s. The orbit intersects that ofEarth nearly exactly, hence streams of material ejected from the comet during perihelion passages do not have to spread out much over time to encounter Earth. This coincidence means that past streams from the comet at perihelion are still dense when they encounter Earth, resulting in the 33-year cycle of Leonid meteor storms. For example, the 1833 meteor storm was created by the previous 1800 perihelion passage.[27] Between 2021–2030, Earth will often pass through the meteoroid stream left behind from the 1733 orbit.[28]
| Numbered comets | ||
|---|---|---|
| Previous 54P/de Vico–Swift–NEAT | 55P/Tempel–Tuttle | Next 56P/Slaughter–Burnham |
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