• The
full moon covers only about of the sky when viewed from the surface of the Earth. The Moon is only a half degree across (i.e. a circular diameter of roughly ), so the moon's disk covers a circular area of ()2, or . The moon varies from 0.188 to depending on its distance from the Earth. • Viewed from Earth, the
Sun is roughly half a degree across (the same as the full moon) and covers only as well. • It would take times the full moon (or the Sun) to cover the entire celestial sphere. • Conversely, an average full moon (or the Sun) covers the fraction 2 / , or less than 1/1000 of a percent () of the celestial hemisphere, or above-the-horizon sky. • Assuming the Earth to be a sphere with a surface area of 510 million square kilometres, the area of
Northern Ireland () represents a solid angle of ,
Connecticut () represents a solid angle of , and
Equatorial Guinea () represents a solid angle of . • The largest constellation,
Hydra, covers a solid angle of , whereas the smallest,
Crux, covers only . == See also ==