Angular size
Angular size is a measurement of how large or small something is using rotational measurement. It is useful for measuring things that are so far away that they appear two dimensional.
Angular Size Media
A 19th century depiction of the apparent size of the Sun as seen from the Solar System's planets (incl. 72 Feronia and the then most outlying known asteroid, here called Maximiliana).
This photo compares the apparent sizes of Jupiter and its four Galilean moons (Callisto at maximum elongation) with the apparent diameter of the full Moon during their conjunction on 10 April 2017.