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

comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ar ...

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 "Solar S ...

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 mem ...

, on August 10, 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. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ellip ...

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

forward scatter In physics, telecommunications, and astronomy, forward scatter is the deflection—by diffraction, nonhomogeneous refraction, or nonspecular reflection by particulate matter of dimensions that are large with respect to the wavelength in question ...

ing reached a peak

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...

of −3. From February 2527, 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 Comet Kohoutek ( formally designated C/1973 E1 and formerly as 1973 XII and 1973f) is a comet that passed close to the Sun towards the end of 1973. Early predictions of the comet's peak brightness suggested that it had the potential to become o ...

in 1973, which had been widely predicted to become extremely prominent: scientists were wary of making predictions that might raise public expectations.Burnham, R. and Levy, D. ''Great Comets'', Cambridge: Cambridge University Press, 2000, p. 73 Comet_West_skypath

Period

With a nearly

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

, 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 Curve fitting is the process of constructing a curve, or mathematical function, that has the best fit to a series of data points, possibly subject to constraints. Curve fitting can involve either interpolation, where an exact fit to the data is ...

orbit for this long-period comet is made more difficult since it underwent a splitting event which may have caused a non-gravitational

perturbation Perturbation or perturb may refer to: * Perturbation theory, mathematical methods that give approximate solutions to problems that cannot be solved exactly * Perturbation (geology), changes in the nature of alluvial deposits over time * Perturbat ...

of the orbit. The 2008

SAO SAO or Sao may refer to: Places * Sao civilisation, in Middle Africa from 6th century BC to 16th century AD * Sao, a town in Boussé Department, Burkina Faso * Saco Transportation Center (station code SAO), a train station in Saco, Maine, U.S. ...

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 1975 August 10 and 1976 January 27, 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.COMETS!: Visitors from Deep Space pg77
/ref> The first report of the split came around 7 March 1976 12:30UT, 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 The Great Comet of 1882 formally designated C/1882 R1, 1882 II, and 1882b, was a comet which became very bright in September 1882. It was a member of the Kreutz Sungrazers, a family of comets which pass within of the Sun's photosphere at perih ...

, a member of the Kreutz Sungrazing 'family' of comets. More recently, comets Schwassmann-Wachmann-3 (73P),

C/1999 S4 C/1999 S4 (LINEAR) was a long-period comet discovered on September 27, 1999, by LINEAR. The comet made its closest approach to the Earth on July 22, 2000, at a distance of . It came to perihelion on July 26, 2000, at a distance of 0.765 AU f ...

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. (Observer Location:@sun)

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

External links