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{{Night Sky
| image =
| designation =M-51
| rightascension =13<sup>h</sup> 29<sup>m</sup> 52.7<sup>s</sup>
| declination =+47° 11′ 43″
| constellation =Canes Venatici
| type =spiral galaxy
| magnitude =8.4
| redshift =0.00155 ± 0.00020
| distance =23 million light years
| radvelocity =463 ± 3 km/s
| propmotion =
| parallax =
}}
The '''Whirlpool galaxy''' (M51, NGC 5194) is a [[spiral galaxy]] in the [[constellation]] of Canes Venatici.<ref name=messier-objects>[http://www.messier-objects.com/messier-51-whirlpool-galaxy/ M51] from messier-objects.com</ref> it is one of the most spectacular galaxies known and one of the easiest to find. It is sometimes called the "Question mark galaxy."<ref name=messier-objects/> The larger galaxy is catalogued as NGC 5194 in the New General catalogue while the smaller galaxy is NGC 5195. Messier 51 can refer to NGC 5194 or both galaxies, though it usually is just NGC 5194. Sometimes NGC 5194 is also called M51a and NGC 5195 is called M51b. It was the first spiral galaxy ever discovered.<ref name=messier-objects/>
==History==
The larger galaxy, NGC 5194 was discovered [[Charles Messier]] in 1773 while he was attempting to observe a [[comet]].<ref name=constellation-guide>[http://www.constellation-guide.com/whirlpool-galaxy-messier-51/ Whirlpool galaxy] from constellation-guide.com</ref> The smaller galaxy was discovered later in 1781 by Messier's colleague, Pierre Méchain. Messier was not able to identify any [star]]s stating the object was a, "very faint nebula without stars." It was not until 1845 that William Parsons' Leviathan, a 72 inch reflecting [[telescope]] identified a spiral structure, the first observed.<ref name=messier-objects/> Wlliam Parsons was the 3<sup>rd</sup> Earl of Rosse, giving another name form the object of "Rosse's galaxy."
==Environment and Structure==
The Whirlpool galaxy has a diameter of 60,000 [[light year]]s and an estimated mass of 160 billion solar masses.<ref>[https://www.nasa.gov/multimedia/imagegallery/image_feature_2457.html The Whirlpool galaxy] from nasa.gov</ref><ref name=constellation-guide/> This is around 35% the size of the [[Milky Way]]. The distance across both galaxies is about 75,000 light years. The smaller galaxy, NGC 5195 is a dwarf galaxy and classified as an [[irregular galaxy]].
The galaxy is believed to have a supermassive [[black hole]] at its centre. The galactic core is fairly active, meaning it is a Seyfert galaxy spcefically, type 2.5.<ref>[http://space-facts.com/whirlpool-galaxy/ Whirlpool galaxy] from space.com</ref><ref>[http://www.messier.seds.org/m/m051.html M51] from messier.seds.org</ref>
==References==
{{reflist}}
{{Galaxies}}
[[Category:Astronomy]]
[[Category:Messier objects]]
| image =
| designation =M-51
| rightascension =13<sup>h</sup> 29<sup>m</sup> 52.7<sup>s</sup>
| declination =+47° 11′ 43″
| constellation =Canes Venatici
| type =spiral galaxy
| magnitude =8.4
| redshift =0.00155 ± 0.00020
| distance =23 million light years
| radvelocity =463 ± 3 km/s
| propmotion =
| parallax =
}}
The '''Whirlpool galaxy''' (M51, NGC 5194) is a [[spiral galaxy]] in the [[constellation]] of Canes Venatici.<ref name=messier-objects>[http://www.messier-objects.com/messier-51-whirlpool-galaxy/ M51] from messier-objects.com</ref> it is one of the most spectacular galaxies known and one of the easiest to find. It is sometimes called the "Question mark galaxy."<ref name=messier-objects/> The larger galaxy is catalogued as NGC 5194 in the New General catalogue while the smaller galaxy is NGC 5195. Messier 51 can refer to NGC 5194 or both galaxies, though it usually is just NGC 5194. Sometimes NGC 5194 is also called M51a and NGC 5195 is called M51b. It was the first spiral galaxy ever discovered.<ref name=messier-objects/>
==History==
The larger galaxy, NGC 5194 was discovered [[Charles Messier]] in 1773 while he was attempting to observe a [[comet]].<ref name=constellation-guide>[http://www.constellation-guide.com/whirlpool-galaxy-messier-51/ Whirlpool galaxy] from constellation-guide.com</ref> The smaller galaxy was discovered later in 1781 by Messier's colleague, Pierre Méchain. Messier was not able to identify any [star]]s stating the object was a, "very faint nebula without stars." It was not until 1845 that William Parsons' Leviathan, a 72 inch reflecting [[telescope]] identified a spiral structure, the first observed.<ref name=messier-objects/> Wlliam Parsons was the 3<sup>rd</sup> Earl of Rosse, giving another name form the object of "Rosse's galaxy."
==Environment and Structure==
The Whirlpool galaxy has a diameter of 60,000 [[light year]]s and an estimated mass of 160 billion solar masses.<ref>[https://www.nasa.gov/multimedia/imagegallery/image_feature_2457.html The Whirlpool galaxy] from nasa.gov</ref><ref name=constellation-guide/> This is around 35% the size of the [[Milky Way]]. The distance across both galaxies is about 75,000 light years. The smaller galaxy, NGC 5195 is a dwarf galaxy and classified as an [[irregular galaxy]].
The galaxy is believed to have a supermassive [[black hole]] at its centre. The galactic core is fairly active, meaning it is a Seyfert galaxy spcefically, type 2.5.<ref>[http://space-facts.com/whirlpool-galaxy/ Whirlpool galaxy] from space.com</ref><ref>[http://www.messier.seds.org/m/m051.html M51] from messier.seds.org</ref>
==References==
{{reflist}}
{{Galaxies}}
[[Category:Astronomy]]
[[Category:Messier objects]]