C / 1769 P1 (Messier)
| C / 1769 P1 (Messier) [i] | |
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The Great Comet
over Nuremberg on the morning of September 9, 1769 |
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| Properties of the orbit ( animation ) | |
| Orbit type | long-period |
| Numerical eccentricity | 0.99925 |
| Perihelion | 0.1228 AU |
| Aphelion | 326.8 AU |
| Major semi-axis | 163.5 AU |
| Sidereal period | ~ 2090 a |
| Inclination of the orbit plane | 40.73 ° |
| Perihelion | October 8, 1769 |
| Orbital velocity in the perihelion | 120.2 km / s |
| history | |
| Explorer | Charles Messier |
| Date of discovery | August 8, 1769 |
| Older name | 1769 |
| Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles . | |
C / 1769 P1 (Messier) was a comet that could be seen with the naked eye in 1769 . Due to its extraordinary brightness, it is counted among the " Great Comets ".
Discovery story
At the Naval Observatory in Paris , Charles Messier was routinely scanning the sky for comets with a telescope when, late in the evening of August 8, 1769, he found a small nebula just above the horizon in the constellation Aries . The next day he could already see it with the naked eye and confirm it as a comet due to its movement in the starry sky.
In the second half of August the comet became more and more visible as it was getting closer and closer to the sun and earth . On August 15, Messier was able to see a tail 6 ° long. Giovanni Domenico Maraldi and César François Cassini de Thury observed the comet from August 22nd, initially with a telescope, later with bare eyes . China's court astronomers reported for the first time on August 24th of a "broom star" in the southeast; Jean François Marie de Surville spotted him on the morning of August 26th from a ship off the Philippines and described him as "curly ... [but] not bright".
However, the brightness of the comet increased more and more. While Eustachio Zanotti observed him on August 28th in Bologna , Messier noticed a 15 ° long tail that same night. James Cook , who sailed the South Pacific on the Endeavor , first saw the comet on the morning of August 30. In the dark sky he was able to follow the tail over 42 °, while Maraldi and Cassini determined only 18 ° longitude a day later. The difference was apparently caused by local visual conditions.
Further observations
The comet was seen from many ships in late August 1769, but these reports contain little additional information. On September 3, Messier saw the comet's tail with a length of 36 °, two days later already with 43 °. The tail now showed a curve, while the comet's head appeared slightly reddish. In the following days, bright parallel rays could be seen in the comet's tail. The tail became longer and longer and on September 9th, Messier measured 55 °.
By the time the comet came closest to Earth on September 10, the tail had already developed to a length of 60 °, according to Messier's observation. On September 11th, Alexandre Guy Pingré observed a tail over 90 ° on a ship between Tenerife and Cádiz, but only the first 40 ° were very bright, while the end of the tail was extremely faint.
In the course of September, the comet became more and more difficult to observe at dusk and the visible tail shrank. Messier saw him for the last time before his approach to the sun on September 16, Maraldi even on September 18 at dusk.
In September, Jérôme Lalande calculated preliminary orbital elements according to which the comet's perihelion should take place on October 7th. From mid-October, many scientists therefore began looking for the comet again. He was found at the Royal Greenwich Observatory on October 23 with a short, broad and weak tail. Messier saw him again a day later in the evening sky - still clearly visible, but difficult to see. In the telescope he observed a bright nucleus and a tail that was only 2 ° short. Joseph-Louis Lagrange saw a pale tail in Milan on October 25 , but a lighter core than in September.
In November the comet was still being followed by many observers, but only Messier wrote down precise descriptions. On November 17th the comet had become even weaker and its tail 1.5 ° long, but after November 18th Messier could no longer see it with the naked eye, further observations were only possible telescopically. The Chinese reported that the comet "completely disappeared" on November 25th. Messier and Maraldi last saw the comet on December 1st, only Pehr Wilhelm Wargentin was able to follow it until the evening of December 3rd.
The comet reached its maximum brightness of 0 mag on September 22nd.
Scientific evaluation
Very similar orbital elements have been calculated for the comet by a large number of astronomers, including Lalande, Giuseppe Asclepi , Cassini, Anders Johan Lexell , Leonhard Euler , Pingré, Adrien-Marie Legendre and Friedrich Wilhelm Bessel . Lexell, Asclepi, Pingré and Bessel even calculated elements for an elliptical orbit.
Orbit
For the comet in 1810 an elliptical orbit could be determined by Bessel from the observation data over a period of 101 days , which is inclined by around 41 ° to the ecliptic . At the point of the orbit closest to the sun ( perihelion ), which the comet passed on October 8, 1769, it was located about 18.4 million km away from the sun, well within the orbit of Mercury . On September 5th it had already approached Venus within 97 million km, while on September 10th it passed the earth at a distance of only 0.323 AU / 48.3 million km. On October 3rd, it came close to Venus again to within 89 million km. The great proximity to the sun and earth was also the reason for its observed brightness.
The comet moves in an extremely elongated elliptical orbit around the sun. According to the railway elements , which are afflicted with a certain uncertainty, it could have appeared in antiquity around the year -330. During the last passage through the inner solar system in 1769, its orbital eccentricity was reduced slightly by 0.00014 and its semi-major axis from about 164 AU to about 140 AU, so that its orbital period was significantly reduced. Therefore, when it reaches the point of its orbit furthest from the sun ( aphelion ) around the year 2590 , it will be about 41.7 billion km from the sun, almost 279 times as far as the earth and more than nine times as far as Neptune . Its orbit speed in aphelion is only about 0.06 km / s. The comet's next perihelion passage may occur around the year 3420.
See also
Web links
- Giovanni Maria Caglieris: La cometa del 1769 e Messier (Italian)
- Felice Stoppa: www.atlascoelestis.com (Italian)
Individual evidence
- ^ AG Pingré: Cométographie ou Traité historique et théorique des comètes . Tome II, Paris, 1784, pp. 83-85.
- ^ GW Kronk: Cometography - A Catalog of Comets, Volume 1. Ancient - 1799 . Cambridge University Press, 1999, ISBN 978-0-521-58504-0 , pp. 442-447.
- ^ DAJ Seargent: The Greatest Comets in History: Broom Stars and Celestial Scimitars . Springer, New York, 2009, ISBN 978-0-387-09512-7 , pp. 121-123.
- ^ Donald K. Yeomans: NASA JPL Solar System Dynamics: Great Comets in History. Retrieved June 17, 2014 .
- ↑ C / 1769 P1 (Messier) in the Small-Body Database of the Jet Propulsion Laboratory (English).
- ↑ SOLEX 11.0 A. Vitagliano. Archived from the original on September 18, 2015 ; accessed on May 2, 2014 .