A constellation is a set of stars in a region of the celestial sphere
which people have decided form a group, typically named after an
image that people find it resembles, of a person, animal, or object.
Examples: Orion, Sagittarius, and Ursa Major.
A constellation's stars are grouped by angular distance but this
does not imply the stars are actually close to each other.
For astronomy, a set of standardized constellations (modern constellations),
generally based upon traditional constellations, are now used to refer
to portions of the sky, i.e., 88 divisions of the sky defined by
the International Astronomical Union (IAU). Names of objects (especially those viewable without
a telescope) often reference the constellations that contain
them, such as traditional stellar designations (Bayer designations
and Flamsteed designations). Galaxy names often use them
as well, e.g., Andromeda and Triangulum. Some of the constellation
names, such as Orion, are commonly referred to in astrophysics
when the constellation contains objects
of study, such as prominent star-forming regions.