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Messier 1 NGC 1952 The Crab Nebula
Imaged
by Martin S. Ferlito copyright
Gstar-EX Integrating Video Camera
8" SCmidt-Cassegrain
on Vixen GP Mount, Stepper Driven.
Information provided by seds.org
Discovered 1731 by British amateur astronomer John Bevis.
The Crab Nebula, Messier 1 (M1, NGC 1952), is the most famous and
conspicuous known supernova remnant, the expanding cloud of gas created in the
explosion of a star as supernova which was observed in the year 1054 AD. It
shines as a nebula of magnitude 8.4 near the southern "horn" of
Taurus, the Bull.
The supernova was noted on July 4, 1054 A.D. by Chinese astronomers as a new
or "guest star," and was about four times brighter than Venus, or
about mag -6. According to the records, it was visible in daylight for 23 days,
and 653 days to the naked eye in the night sky. It was probably also recorded
by Anasazi Indian artists (in present-day Arizona and New Mexico), as findings
in Navaho Canyon and White Mesa (both Arizona) as well as in the Chaco Canyon
National Park (New Mexico) indicate; there's a review of the research on the Chaco
Canyon Anasazi art online. In addition, Ralph R. Robbins of the University of
Texas has found Mimbres Indian art from New Mexico, possibly depicting the
supernova.
The Supernova 1054 was also assigned the variable star designation CM Tauri.
It is one of few historically observed supernovae in our Milky Way Galaxy.The nebulous remnant was discovered by John Bevis in 1731, who added it to
his sky atlas, Uranographia Britannica. Charles Messier independently found
it on August 28, 1758, when he was looking for comet Halley on its first
predicted return, and first thought it was a comet. Of course, he soon
recognized that it had no apparent proper motion, and cataloged it on September
12, 1758. It was the discovery of this object which caused Charles Messier to
begin with the compilation of his catalog. It was also the discovery of this
object, which closely resembled a comet (1758 De la Nux, C/1758 K1) in his
small refracting telescope, which brought him to the idea to search for comets
with telescopes (see his note). Messier acknowledged the prior, original
discovery by Bevis when he learned of it in a letter of June 10, 1771.
Although Messier's catalog was primarily compiled for preventing confusion
of these objects with comets, M1 was again confused with comet Halley on the
occasion of that comet's second predicted return in 1835.
The nebula consists of the material ejected in the
supernova explosion, which has been spread over a volume approximately 10 light
years in diameter, and is still expanding at the very high velocity of about
1,800 km/sec. The notion of gaseous filaments and a continuum background was
photographically confirmed by Walter Baade and Rudolph Minkowski in 1930: The
filaments are apparently the remnants from the former outer layers of the
former star (the "pre-supernova" or supernova
"progenitor"), while the inner, blueish nebula emits continuous light
consisting of highly polarised so-called synchrotron radiation, which is
emitted by high-energy (fast moving) electrons in a strong magnetic field. This
explanation was first proposed by the Soviet astronomer J. Shklovsky (1953) and
supported by observations of Jan H. Oort and T. Walraven (1956).
