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Observed structure of the Milky Way's spiral arms
The 'Sagittarius Arm' (also known as ''Sagittarius-Carina Arm''; labeled "-I") is one of the
spiral arms of our home
galaxy, the
Milky Way. Each spiral arm is a long, diffuse curving streamer of
stars that radiates out from the
galactic center. These gigantic structures are often composed of billions of stars, and Sagittarius is one of the largest arms in our galaxy.
The Milky Way is a
barred spiral galaxy, consisting of a central crossbar from which several spiral arms radiate outwards. The Sagittarius Arm's innermost end connects to one of the ends of this central bar, making it one of the two major spiral arms of the galaxy. The other large arm is the
Cygnus Arm.
The dense, inner arm of Sagittarius is located between the
Scutum-Crux Arm and the
Orion Arm (the Orion arm is marked as the Local Spur on the galactic map, and Orion also contains our sun). It is named for its proximity to the
Sagittarius constellation as seen in the
night sky from Earth, in the direction of the
galactic center.
The Sagittarius Arm is divided into two parts. Curving outward from the galaxy's central bar is the Sagittarius Arm (Sagittarius bar), which further outward becomes the Carina arm.
Visible Objects
A number of
Messier objects, objects that are visible through an amateur's telescope or binoculars, are found in the Sagittarius Arm.
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M8, the Lagoon Nebula
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M11, the Wild Duck Cluster
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M16, the Eagle Nebula
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M17, the Omega Nebula
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Open Cluster M18
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M20, the Trifid Nebula
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Open Cluster M21
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M24, the Sagittarius Star Cloud
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Open Cluster M26
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Globular Cluster M55
Other resources
See also
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List of Messier objects
External links
★ http://members.fcac.org/~sol/chview/chv5.htm
★ http://skyandtelescope.com/mm_images/6829.jpg
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Messier Objects in the Milky Way (SEDS)