Changes

| rightascension  =05^h 34^m 31.97^s  

| rightascension  =05^h 34^m 31.97^s  

| declination    =+22^o 00′ 52.1"

| declination    =+22^o 00′ 52.1"

| distance        =6,500 ± 1,600 ly

| distance        =

| constellation  =[[Taurus]]  

| constellation  =[[Taurus]]  

| type            =[[nebula]], [[supernova|supernova remnant]]   

| type            =[[nebula]], [[supernova|supernova remnant]]   

==Supernova Event==

==Supernova Event==

The Crab Nebula is the result of the supernova event called '''SN1054''', which was first recorded by [[Chinese]] and [[Arab]] astronomers on July 4th, 1054 A.D. as a "guest star".  The event was possibly also the inspiration for astronomy related art created by [[Anasazi]] [[Indians]].<ref>http://www.astronomy.pomona.edu/archeo/outside/chaco/nebula.html</ref> Initially the supernova had an apparent magnitude of -6, making it brighter then even [[Venus]].  The star then began to fade, but remained subsequently bright enough to be observed during the day for the next 23 days, and at night for the next 653 days before finally fading from view.<ref>http://www.seds.org/messier/more/m001_sn.html</ref> The supernova has been classified since with the variable star designation '''CM Tauri'''.  

The Crab Nebula is the result of the supernova event called '''SN1054''', which was first recorded by [[Chinese]] and [[Arab]] astronomers on July 4th, 1054 A.D. as a "guest star".  The event was possibly also the inspiration for astronomy-related art created by [[Anasazi]] [[Indians]].<ref>http://www.astronomy.pomona.edu/archeo/outside/chaco/nebula.html</ref> Initially the supernova had an apparent magnitude of -6, making it brighter then even [[Venus]].  The star then began to fade, but remained subsequently bright enough to be observed during the day for the next 23 days, and at night for the next 653 days before finally fading from view.<ref>http://www.seds.org/messier/more/m001_sn.html</ref> The supernova has been classified since with the variable star designation '''CM Tauri'''.  

The progenitor star for the explosion is calculated to be between 9 and 11 solar masses, this is based on theoretical models of supernova explosions.<ref>http://adsabs.harvard.edu/abs/1985cnrs.work...97N</ref>

Based on theoretical models of supernova explosions, the progenitor star for the explosion is calculated to have been between 9 and 11 solar masses.<ref>http://adsabs.harvard.edu/abs/1985cnrs.work...97N</ref>

==History of Observation==

==History of Observation==

The name "Crab Nebula" itself originated from a drawing of the nebula made by '''Lord Rosse''' in 1844, where the supernova remnant looked like a crab.<ref>http://seds.org/MESSIER/more/m001_rosse.html</ref>

The name "Crab Nebula" itself originated from a drawing of the nebula made by '''Lord Rosse''' in 1844, where the supernova remnant looked like a crab.<ref>http://seds.org/MESSIER/more/m001_rosse.html</ref>

In 1892 the first [[photograph]] was taken of the nebula using a 20 inch [[telescope]].  Later in 1921 it was discovered that the nebula was expanding at a rate that allowed for the tracing of its origin to about 900 years before.<ref>http://adsabs.harvard.edu/abs/1921PNAS....7..179D</ref>  Meanwhile, independently in the same year it was realized that the nebula was also in the same proximity as the supernova SN1054, these two observations lead to the revelation the nebula was the remnant of that same supernova event.<ref>http://adsabs.harvard.edu/abs/1921PASP...33..225L</ref>

In 1892 the first [[photograph]] was taken of the nebula using a 20 inch [[telescope]].  Later in 1921 it was discovered that the nebula was expanding at a rate that allowed for the tracing of its origin to about 900 years before.<ref>http://adsabs.harvard.edu/abs/1921PNAS....7..179D</ref>  In the same year it was independently realized that the nebula was in the proximity of the supernova SN1054.  These two observations led to the revelation that the nebula was the remnant of that same supernova event.<ref>http://adsabs.harvard.edu/abs/1921PASP...33..225L</ref>

Later in 1949, the nebula was discovered to be a strong source of [[radio waves]].<ref>http://adsabs.harvard.edu/abs/1949Natur.164..101B</ref>  In 1963 it was discovered the nebula was also a major source of [[x-rays|x-ray]], emitting x-ray [[radiation]] at 100 times the energy the nebula emits energy in the visual spectrum.<ref>http://www.sciencemag.org/cgi/content/abstract/146/3646/912</ref> Eventually the source of this energy was discovered in 1968, when a radio [[pulsar]], later revealed to be a neutron star, was found.

Later in 1949, the nebula was discovered to be a strong source of [[radio waves]].<ref>http://adsabs.harvard.edu/abs/1949Natur.164..101B</ref>  In 1963 it was discovered that the nebula was also a major source of [[x-rays|x-ray]], emitting x-ray [[radiation]] at 100 times the energy the nebula emits energy in the visual spectrum.<ref>http://www.sciencemag.org/cgi/content/abstract/146/3646/912</ref> Eventually the source of this energy was discovered in 1968, when a radio [[pulsar]], later revealed to be a neutron star, was found.

==Properties==

==Properties==

Despite being one of the best known nebula, the Crab Nebula isn't visible to the unaided eye with an apparent magnitude of only +8.4  The exact distance of the nebula itself is uncertain but is estimated around 6,500 ± 1,600 light years away.<ref>http://adsabs.harvard.edu/abs/2008arXiv0801.1142K</ref>  It is roughly some 11 light years across overall, extending some 13 light years across at its longest.  Right now the nebula's gasses are expanding at around 1500 km/s, and is believed accelerating due to energy emitting from the pulsar. The amount of matter in the nebula is estimated to be around 4.6 ± 1.8 solar masses, and is used to help estimate the total mass of the progenitor star.<ref>http://adsabs.harvard.edu/abs/1997AJ....113..354F</ref>

Despite being one of the best known nebulae, the Crab Nebula is invisible to the unaided eye, with an apparent magnitude of only +8.4  The exact distance of the nebula itself is unknown. It is roughly 11 light years across overall, extending some 13 light years across at its longest.  Right now the nebula's gasses are expanding at around 1500 km/s, and it is believed that this velocity is increasing due to energy emitted from the pulsar. The amount of matter in the nebula is estimated to be around 4.6 ± 1.8 solar masses, and is used to help estimate the total mass of the progenitor star.<ref>http://adsabs.harvard.edu/abs/1997AJ....113..354F</ref>

===Crab Pulsar===

===Crab Pulsar===