مشارکتکنندگان ویکیپدیا، «Orion Arm»، ویکیپدیای انگلیسی، دانشنامهٔ آزاد. (بازیابی در ۱۱ دسامبر ۲۰۰۷).
The Orion Arm is a minor spiral arm of the Milky Way Galaxy that is 3,500 light-years (1,100 parsecs) across and approximately 10,000 light-years (3,100 parsecs) in length, containing the Solar System, including Earth. It is also referred to by its full name, the Orion–Cygnus Arm, as well as Local Arm, Orion Bridge, and formerly, the Local Spur and Orion Spur.
The arm is named for the Orion Constellation, which is one of the most prominent constellations of Northern Hemisphere winter (Southern Hemisphere summer). Some of the brightest stars and most famous celestial objects of the constellation (e.g. Betelgeuse, Rigel, the three stars of Orion's Belt, the Orion Nebula) are within it as shown on the interactive map below.
The arm is between the Carina–Sagittarius Arm (the local portions of which are toward the Galactic Center) and the Perseus Arm (the local portion of which is the main outer-most arm and one of two major arms of the galaxy).
Long thought to be a minor structure, namely a "spur" between the two arms mentioned, evidence was presented in mid 2013 that the Orion Arm might be a branch of the Perseus Arm, or possibly an independent arm segment.
Within the arm, the Solar System is close to its inner rim, in a relative cavity in the arm's Interstellar Medium known as the Local Bubble, about halfway along the arm's length, approximately 8,000 parsecs (26,000 light-years) from the Galactic Center.
The Orion Arm contains a number of Messier objects: