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Astro*Dictionary by Michael Erlewine





2 articles for "Comet/s"

Comet [Astro*Index]

Celestial bodies with exaggerated parabolic orbits. Periodicity is uncertain except for those which have been cited numerous times, such as Haley's Comet. Comets are chunks of loosely packed frozen gases such as carbon dioxide, methane, and ammonia, plus ordinary ice, which orbit the sun in long elliptical orbits, and spend most of their time at the far reaches of our solar system. At long intervals, of up to ten thousand years, they move close to the Sun, which partially melts them and evaporates some of the gases. The solar wind catches these luminous gas particles, and blows them out into a long streaming tail, stretching away from the Sun for millions of kilometers. Comets have long fascinated man, and were believed to be omens of revolutions and other catastrophic events. Halley's comet, a famous periodic comet which orbits the Sun in about 75 years, made an appearance in l986.

See also:
♦ Solar Wind
Comets [DeVore]

Erratic members of the Solar system, usually of small mass. Luminous bodies, wandering through space, or circulating around the Sun, and visible only when they approach the Sun. They usually consist of three elements: nucleus, envelope, and tail. The superstitious once considered them to be evil omens. Those pursuing an elongated orbit are periodic and return at fixed intervals. Those with a parabolic or hyperbolic orbit are expected never to return.

The astrological significance of comets has been the subject of much study, but so far no definite conclusions have been reached. Suggestion has been advanced that Donate's comet, which made its first appearance of record in June 1858 and attained its maximum brilliancy on October 9th, was a factor in the nativity of Theodore Roosevelt, born October 27, 1858. It is presumed that comets presage history-making events; but operating through individuals whose birth coincides with their appearance, their effects are so delayed as often to be overlooked. Donati's comet was one of the most beautiful of comets. Its tall was curved. The nucleus had a diameter of 5,600 miles.

"When beggars die there are no comets seen;
The heavens themselves blaze forth the death of princes."



The year of F. D. Roosevelt's birth was also marked by the appearance of one of the brightest comets of record, which was visible in broad daylight - even at noon.

List of Periodic Comets

The following lists of comets afford a basis for their further study:


Periodic Comets     PeriodDistance    
from Sun *   
Incl. to
Barnard's (1884)5.40       1.28 -   4.895°28'     1906.2
Barnard's (1892)6.31       1.43 -   5.3831°40'     1905.6
Biela's6.69       0.88 -   6.2212°22'     1866.1
Brooks's7.10       1.96 -   5.436°04'     1903.9
Brorsen's5.46       0.59 -   5.6129°24'     1890.2
Cunningham's     1940.9
D'Arrest's6.69       1.33 -   5.7715°43'     1897.4
DeVico-E. Swift's6.40       1.67 -   5.223°35'     1901.1
Donati's5000.00           1858.8
Encke's3.30       0.34 -   4.0912°36'     1905.1
Faye's7.39       1.65 -   5.9410°38'     1903.4
Finlay's6.56       0.97 -   6.043°03'     1900.2
Halley's76.08       0.69 - 35.22162°13'     1910.3
Holmes's6.87       2.13 -   5.120°48'     1899.3
Olters's72.65       1.02 - 33.6244°34'     1887.8
Pons-Brooks's71.56       0.78 - 33.774°3'     1884.1
Temple's6.54       2.09 -   4.9010°47'     1898.8
Temple's5.28       1.39 -   4.6812°39'     1904.8
Temple-L. Swift's5.68         1.15 - 5.215°26'     1903.1
Tuttle's13.67       1.02 - 10.4154°29'     1899.3
Winnecke's5.83       0.92 -   5.5517°00'     1004.1
Wolf's6.82       1.59 -   5.6025°15'     1905.3
*In terms of Earth's Mean Distance.


Cunningham's Comet, first observed in 1940, had a tail of an estimated length of 60 million miles, pointing directly upward. It was of a magnitude of 1.7.

Halley's Comet, 1835 and 1910, is the most historic comet. Every appearance has been traced back to 240 B.C.

The head of Holmes's Comet had a diameter in excess of a million miles. It is one of the largest of record.

The great comet of 1843, which seems not to have been given a name, was apparently a Periodic Comet, with an orbit of 400 years. A tail 200 million miles in length, the longest tail of any comet of record, made it a sight of grandeur. Its perihelion distance, 300,000 miles, was extremely short, and carried it through the Sun's corona.

Non-Periodic Comets

Among the records of non-periodic comets are:

Great comet of 1729.
The greatest of record, yet details are lacking. Its perihelion distance, approximately 384 million miles, over four times distance of sun to earth, brought it no closer to Sun than Jupiter's orbit, although it did go around the Sun. Had it come as close as the average comet, its splendor would have transcended that of any other comet.

De Cheseaux's Comet, 1744
An unusual comet, six tails.

Great Comet of 1811.
The largest comet in actual size ever observed, except the 1729 comet of which little is known. The head was 1,125,000 miles in diameter – larger than the Sun. The tail was 100,000,000 miles in length. It was a magnificent sight. Its aphelion-distance was 14 times the distance of Neptune from the Sun. The wine in France was particularly good that season, and for years was famed as "Comet Wine."

Great Comet of 1861.
Earth passed through the tail which subtended over 100° of arc. At one time the comet was brighter than any star or planet except Venus at its brightest, and a peculiar glow suffused the entire sky. One of the finest, probably the brightest comet. Could be seen in broad daylight, even at noon.

Morehouse's Comet, 1908.
Showed the most rapid variations in appearance – the tail changing so much from day to day that sometimes it could not be recognized as the same comet.

Comet 1925a.
In perihelion distance it was one of the largest – nearly as far away as Jupiter.

Collision with Earth.
On June 30, 1908, occurred in Siberia the greatest meteorite fall in historic times. It was probably the head of a small comet. It had no connection with Morehouse's Comet. Another and larger collision caused Meteor Crater in Arizona, but it was pre-historic-probably 40,000 years ago.

See also:
♦ Solar Wind


Astro*Index Copyright © 1997 Michael Erlewine


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