The Local Arm of the Milky Way and the Sun's Changing Place. Dr. Ken Croswell discusses new revelations about the Milky Way, a spiral galaxy. The Sun is in the local arm, also called the Orion arm, which is a vigorous star nursery containing the Orion Neb

The Local Arm of the Milky Way and the Sun's Changing Place. Dr. Ken Croswell discusses new revelations about the Milky Way, a spiral galaxy. The Sun is in the local arm, also called the Orion arm, which is a vigorous star nursery containing the Orion Nebula. Previously considered a minor spur, the local arm is now known to be substantial, extending at least 26,000 light-years. Observations rely on maser parallaxes measured by radio telescopes and precise data from the optical Gaia spacecraft. The Sun is not a permanent resident of this arm.