Stephenson 2-18 size and scale context

Stephenson 2-18 is a very cool, luminous red supergiant candidate in the direction of the Stephenson 2 stellar association. It has been given one of the largest published stellar size estimates, but its exact diameter remains uncertain because the star is distant, dust-affected, and difficult to separate cleanly from its surrounding region. Read its scale context, comparisons, and journey links on the canonical object page.