Want to stay on top of all the space news? Follow @universetoday on TwitterComet West, officially known as C/1975 V1, 1976 VI, and 1975n, was an awesome comet that was sometimes considered to qualify for the status of great comet. A Great Comet is a comet that becomes exceptionally bright; there is no official definition, often the term will be attached to comets that become bright enough to be noticed by casual observers who are not actively looking for them, and become well known outside the astronomical community. Great Comets are rare; on average only one will appear in a decade. While comets are officially named after their discoverers, Great Comets are sometimes also referred to by the year in which they appeared great.
Comet West was different from most comets because it was so very bright. The vast majority of comets are never bright enough to be seen by the naked eye, and generally pass through the inner solar system unseen by anyone except astronomers. However, occasionally a comet may brighten to naked eye visibility, and even more rarely it may become as bright or brighter than the brightest stars. The requirements for this to occur are: a large and active nucleus, a close approach to the Sun, and a close approach to the Earth. A comet fulfilling all three of these criteria will certainly be spectacular.
Comet West was discovered in photographs by Richard West on August 10, 1975 and reached peak brightness in March 1976, attaining a brightness of -3 at perihelion. During peak brightness, observers reported that it was bright enough to study during full daylight. Despite its spectacular appearance, Comet West went largely unreported in the popular media. The comet has an estimated orbital period of 558,000 years. The comets nucleus broke into four parts during its trip through the inner solar system.
There are several good articles on the internet about Comet West. One of the best is here and another good one is here. We have a great article here on Universe Today about how the Tunguska event may have been a comet. Astronomy Cast has a nice episode that makes a case that the Christmas Star was a comet.