 A celestial map detailing the path of Comet Sarabat across the sky byJacques Cassini | |
| Discovery | |
|---|---|
| Discovered by | Fr.Nicolas Sarabat |
| Discovery site | Nîmes, France |
| Discovery date | 1 August 1729 |
| Designations | |
| Comet of 1729 | |
| Orbital characteristics[1] | |
| Epoch | 16 June 1729 (JD 2352731.148) |
| Observation arc | 135 days |
| Number of observations | 3 (very poorly determined) |
| Perihelion | 4.05054AU |
| Eccentricity | ~1.000 (assumed) |
| Inclination | 77.095° |
| 314.393° | |
| Argument of periapsis | 10.403° |
| Last perihelion | 16 June 1729 |
| Next perihelion | Ejection trajectory (assumed) |
| Physical characteristics[2][3] | |
Mean diameter | ~100 km (62 mi) |
| Comet total magnitude (M1) | –3.0 |
| 3–4 (1729 apparition) | |
TheComet of 1729, also known asC/1729 P1 orComet Sarabat, was an assumedparabolic comet with anabsolute magnitude of −3,[2][4] possibly the brightest ever observed for a comet;[a] it is therefore considered to be potentially the largest comet ever seen.[6] With an assumed eccentricity of 1,[1] it is unknown if this comet will return in a hundred thousand years or be ejected from the Solar System.
Thecomet was discovered in the constellation ofEquuleus by FatherNicolas Sarabat, a professor of mathematics, atNîmes in the early morning of August 1, 1729.[7] At the time of discovery the comet was making its closest approach to Earth at a distance of 3.1 AU (460 million km; 290 million mi) and had asolar elongation of 155 degrees.[8]
Observing with the naked eye, he saw an object resembling a faint, nebulous star: he was at first unsure if it was a comet or part of theMilky Way. Moonlight interfered with Sarabat's observations until August 9, but after recovering the object and attempting to detect its motion without the aid of any measuring instruments, he became convinced that he had found a new comet.[8]
News of the discovery was passed toJacques Cassini inParis. He was able to confirm the comet's position, though with extreme surprise at how little it had moved since the first observation nearly a month previously. Cassini was able to continue observation until 18 January 1730, by which time the comet was located inVulpecula. This was an extraordinarily long period for observation of a comet, though it never rose aboveapparent magnitude 3–4, about the brightness of theAndromeda Galaxy.
The comet's orbit, later computed byJohn Russell Hind, showed aperihelion distance (closest approach to the Sun) of 4.05 AU (606 million km), which is just within the orbit ofJupiter.[1] However, despite this it became visible (although faintly) to the naked eye, and indeed remained visible for six months in total. This suggests that itsabsolute magnitude or intrinsic brightness was unusually high, possibly as high as −3.0.[2][4] It is therefore likely that the Comet of 1729 was an exceptionally large object, with acometary nucleus on the order of 100 km (62 mi) in diameter.[3] The JPL small-body database only uses three observations, atwo-body model, and an assumedepoch to compute the orbit of this assumedparabolic comet.[1] With such a limited dataset, undefineduncertainties, and an assumed eccentricity of 1,[1] (that is, a parabolic trajectory) it is unknown if the comet will returnon the order of 100,000 years or be ejected from the Solar System.
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