Orion Arm

The Orion Arm is a minor spiral arm of the Milky Way between the Sagittarius and Perseus arms. It contains the Solar System.

Milky Way: The barred spiral galaxy that contains the Solar System and billions of other stars. The Orion Arm is one of the Milky Way’s spiral structures.
Perseus Arm: A major spiral arm of the Milky Way beyond the Orion Arm from the Galactic center. It is one of the two major arms flanking the Orion Arm.
Density wave theory: A model in which spiral patterns move through a galactic disk as density waves, rather than as fixed groups of stars. It offers one explanation for persistent spiral structure in the Milky Way.
Solar System: The Sun and the celestial objects gravitationally bound to it. It is located within the Orion Arm.
Milky Way mapping: The observational effort to chart the Milky Way’s structure, contents, and distances from within it. Mapping determines where the Orion Arm begins, ends, and connects to other structures.
Spiral arm: A long, curved region of enhanced star formation and density within a spiral galaxy. The Orion Arm is a relatively small example of this galactic structure.
Sagittarius Arm: A major spiral arm of the Milky Way lying inward from the Orion Arm. It is the Orion Arm’s neighboring arm toward the Galactic center.
Differential rotation: Rotation in which different parts of a system orbit at different angular speeds. The Milky Way’s varying rotation rates affect the shape and winding of its arms.
Orion Nebula: A bright star-forming nebula in the constellation Orion, about 1,300 light-years from Earth. It is a nearby, prominent site of star formation in the arm.
Very Long Baseline Array: A network of radio telescopes that combines observations to achieve extremely high angular resolution. Its measurements of masers help map star-forming regions in the arm.

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Location of EarthBroader topic: The Solar System lies within this galactic structure.