"Angular diameter" refers to the size of an object as it appears from a particular viewpoint, measured in degrees. It describes how large an object appears to be when observed from a specific location.
Sentences with «angular diameter»
It appears quite small without a telescope because only the central part is bright enough to be visible, but the full angular diameter of the galaxy is seven times that of the full moon. (sciencedaily.com)
Note that this effect of size on the perceived contrast can not be explained by the finite resolution of the visual system, because we used disks with angular diameter much larger than that of the Airy disk, and the effect was exactly the same for disks of the two different diameters we used. (jov.arvojournals.org)
[8] The estimated angular diameter of this star is about 0.92 mas. (en.wikipedia.org)