Comet West, formally designated as C/1975 V1, 1976 VI, and 1975n, was a

comet A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...

described as one of the brightest objects to pass through the inner

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

in 1976. It is often described as a "

great comet A great comet is a comet that becomes exceptionally bright. There is no official definition; often the term is attached to comets such as Halley's Comet, which during certain appearances are bright enough to be noticed by casual observers who ar ...

History

It was discovered photographically by Richard M. West, of the

European Southern Observatory The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental organization, intergovernmental research organisation made up of 16 m ...

, on 10 August 1975. The comet came to

perihelion An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...

(closest approach to the Sun) on 25 February 1976. During perihelion the comet had a minimum solar elongation of 6.4° and as a result of

forward scatter Forward scattering is the deflection of waves by small angles so that they continue to move in close to the same direction as before the scattering. It can occur with all types of waves, for instance light, ultraviolet radiation, X-rays as well as ...

ing reached a peak

apparent magnitude Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

of −3. From 25 to 27 February, observers reported that the comet was bright enough to study during full daylight. Despite its brightness, Comet West went largely unreported in the popular media. This was partly due to the relatively disappointing display of Comet Kohoutek in 1973, which had been widely predicted to become extremely prominent: scientists were wary of making predictions that might raise public expectations. ''

The New York Times ''The New York Times'' (''NYT'') is an American daily newspaper based in New York City. ''The New York Times'' covers domestic, national, and international news, and publishes opinion pieces, investigative reports, and reviews. As one of ...

'', however, reported this about Comet West on 2 March 1976:

Period

With a nearly

parabolic trajectory In astrodynamics or celestial mechanics a parabolic trajectory is a Kepler orbit with the Orbital eccentricity, eccentricity equal to 1 and is an unbound orbit that is exactly on the border between elliptical and hyperbolic. When moving away f ...

, estimates for the

orbital period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets ...

of this comet have varied from 254,000 to 558,000 years. Computing the best-fit orbit for this long-period comet is made more difficult since it underwent a splitting event which may have caused a non-gravitational perturbation of the orbit. The 2008 SAO Catalog of Cometary Orbits shows 195 observations for C/1975 V1 and 135 for C/1975 V1-A, for a combined total of 330 (218 observations were used in the fit).

Breakup

Before the

passage, and using 28 positions obtained between 10 August 1975 and 27 January 1976, Comet West was estimated to have an orbital period of about 254,000 years. As the comet passed within 30 million km of the Sun, the nucleus was observed to split into four fragments. The first report of the split came around 7 March 1976 at 12:30 UTC, when reports were received that the comet had broken into two pieces. Astronomer Steven O'Meara, using the 9-inch Harvard Refractor, reported that two additional fragments had formed on the morning of 18 March. The fragmentation of the nucleus was, at the time, one of very few comet breakups observed, one of the most notable previous examples being the Great Comet of 1882, a member of the Kreutz Sungrazing 'family' of comets. More recently, comets Schwassmann-Wachmann-3 (73P), C/1999 S4 LINEAR, and 57P/du Toit-Neujmin-Delporte, have been observed to split or disintegrate during their passage close to the Sun. The comet has been more than from the Sun since 2003.

Nomenclature

In the nomenclature of the time, it was known as ''Comet 1976 VI'' or ''Comet 1975n'', but the modern nomenclature is ''C/1975 V1''. (Note that "1976 VI" uses the Roman numeral VI = 6, while "C/1975 V1" is the letter V and the number 1).

References

Notes

Citations

External links

* {{DEFAULTSORT:West, 1975 V1 Non-periodic comets 19750810 Great comets Split comets