 Large Magellanic Cloud

The Large Magellanic Cloud is a nearby galaxy interacting with the Milky Way, containing stars whose independently measurable properties help calibrate astronomical distances. Its proximity makes it possible to combine stellar observations that are much harder to separate in more distant systems.

In a late-type eclipsing binary, orbital velocities and eclipse geometry constrain linear stellar sizes; a surface-brightness calibration supplies corresponding angular sizes. Comparing the two gives a distance anchor rather than assuming one fixed luminosity for every star.^[ref] Such calibration still has systematic uncertainty and samples a galaxy with finite depth.

One of the brightest natural objects in the sky, and by far the brightest not in the Milky Way! This is partly because it is relatively close to us.