asterism

An asterism is a group of visible stars that is easily recognizable, such as Orion's belt or the Big Dipper. They can be useful to help orient yourself regarding the portion of the celestial sphere you are looking at, e.g., for celestial navigation or casual astronomy. An asterism may be a constellation, or the prominent stars of a constellation, but could also be a portion of a constellation or include parts of more than one. A telescopic asterism is one only viewable (or most easily discerned) using a telescope.

In ancient times a constellation was a "picture" perceived in the position of stars, adopted for use when discussing the stars for much the same reason as asterisms. This usage has been developed into a set of 88 (the modern constellations), each corresponding to a region of the celestial sphere, many of them based upon ancient constellations, having been standardized for use as part of the names of stars and other objects within the given region.

The term starfield refers to those stars within an area of the celestial sphere that could easily be the field of view of a telescope. A common use of the term is for the group of stars surrounding some star or other object of interest, e.g., "the starfield of Sirius".

The term visual grouping is basically like asterism, but can be items other than stars, e.g., galaxies that are grouped near each other in the sky.