The second step was to determine its actual diameter, in light years.

The actual diameter of the 8.1mm is 0.318898 inches.

The integer sizes can be converted to the actual diameter by using the formula 0.060 + 0.013 * number.

The actual diameter of the round didn't change.

This allows a direct calculation of the actual diameter, which is in good agreement with the 1,050 solar radii derived by other methods.

The distance to the object can therefore be estimated by knowing its actual diameter and measuring its angular size.

Because of foreshortening, it may be quite different from the actual physical diameter for an object that is seen under an angle.

For a spherical object at a large distance, the visual and actual diameters are the same.

For practical use, the distinction between the visual diameter and the actual diameter only makes a difference for spherical objects that are relatively close.

At the cluster's estimated distance of 980 light years this corresponds to an actual diameter of 25 light years.