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Created page with "{{Night Sky | image = | designation =Messier 17 NGC 6618 | rightascension =18<sup>h</sup> 20<sup>m</sup> 26<sup>s</sup> | declination..."
{{Night Sky
| image =
| designation =[[Messier catalogue|Messier 17]]
NGC 6618
| rightascension =18<sup>h</sup> 20<sup>m</sup> 26<sup>s</sup>
| declination =-16° 10′ 36″
| distance =5,000-6,000 ly
| constellation =[[Sagittarius]]
| type =[[Emission nebula]]
| dimensions = 11'
| magnitude = 6.0
| redshift =
| radvelocity =
| propmotion =
| parallax =
}}
The '''Omega nebula''' (M17, NGC 6618) is famous an [[emission nebula]] in the [[constellation]] of [[Sagittarius]].<ref name=seds>[http://www.messier.seds.org/m/m017.html M17] from messier.seds.org</ref> Sometimes called the Swan nebula, the Horseshoe nebula or the Lobster nebula, it is named for its resemblance to the [[Greek alphabet|Greek]] letter [[omega]], Ω. Like many emission nebulae, it is illuminated by a star cluster within the nebula but unlike most nebulae, the nebulae obscures these stars in the [[visible light|visible]]. It is found not far from the [[Trifid nebula]], the [[lagoon nebula]] and the [[Eagle nebula]].
==History==
The first observation of the Omega nebula was made in 1745 by Jean-Philippe Loys de Chéseaux.<ref name=seds/> It was independently discovered by [[Charles Messier]] on 3<sup>rd</sup> June 1764.<ref name=messier-objects>[http://www.messier-objects.com/messier-17-omega-nebula/ Omega nebula] from constellation-guide.com</ref> [[William Herschel]]'s son, John, first noticed its resemblence to the letter omega. Admiral William Henry Smyth decided it appeared like a horseshoe and named it so in 1836.<ref name=messier-objects/>
==Properties and Structure==
The nebula has a diameter of 15 light years and is part of a larger cloud that is at least 40 light years across.<ref name=messier-objects/> One of the larger H II (cloud of [[ionization|ionized]] [[hydrogen]]) in the galaxy, it is believed to have a [[mass (science)|mass]] of 800 solar masses. The [[open cluster]] housed within the nebula of 35 stars which illuminate the cloud. The nebula itself contains at least 800 stars. The gas an dust present in the the nebula prevent event the brightest of these stars being visible.
==References==
{{reflist}}
{{Nebulae}}
[[Category:Astronomy]]
[[Category:Nebulae]]
[[Category:Messier Objects]]
| image =
| designation =[[Messier catalogue|Messier 17]]
NGC 6618
| rightascension =18<sup>h</sup> 20<sup>m</sup> 26<sup>s</sup>
| declination =-16° 10′ 36″
| distance =5,000-6,000 ly
| constellation =[[Sagittarius]]
| type =[[Emission nebula]]
| dimensions = 11'
| magnitude = 6.0
| redshift =
| radvelocity =
| propmotion =
| parallax =
}}
The '''Omega nebula''' (M17, NGC 6618) is famous an [[emission nebula]] in the [[constellation]] of [[Sagittarius]].<ref name=seds>[http://www.messier.seds.org/m/m017.html M17] from messier.seds.org</ref> Sometimes called the Swan nebula, the Horseshoe nebula or the Lobster nebula, it is named for its resemblance to the [[Greek alphabet|Greek]] letter [[omega]], Ω. Like many emission nebulae, it is illuminated by a star cluster within the nebula but unlike most nebulae, the nebulae obscures these stars in the [[visible light|visible]]. It is found not far from the [[Trifid nebula]], the [[lagoon nebula]] and the [[Eagle nebula]].
==History==
The first observation of the Omega nebula was made in 1745 by Jean-Philippe Loys de Chéseaux.<ref name=seds/> It was independently discovered by [[Charles Messier]] on 3<sup>rd</sup> June 1764.<ref name=messier-objects>[http://www.messier-objects.com/messier-17-omega-nebula/ Omega nebula] from constellation-guide.com</ref> [[William Herschel]]'s son, John, first noticed its resemblence to the letter omega. Admiral William Henry Smyth decided it appeared like a horseshoe and named it so in 1836.<ref name=messier-objects/>
==Properties and Structure==
The nebula has a diameter of 15 light years and is part of a larger cloud that is at least 40 light years across.<ref name=messier-objects/> One of the larger H II (cloud of [[ionization|ionized]] [[hydrogen]]) in the galaxy, it is believed to have a [[mass (science)|mass]] of 800 solar masses. The [[open cluster]] housed within the nebula of 35 stars which illuminate the cloud. The nebula itself contains at least 800 stars. The gas an dust present in the the nebula prevent event the brightest of these stars being visible.
==References==
{{reflist}}
{{Nebulae}}
[[Category:Astronomy]]
[[Category:Nebulae]]
[[Category:Messier Objects]]