- Local Group (Wikipedia)
The Local Group is the galaxy group that includes the Milky Way. It has a total diameter of roughly 3 megaparsecs (10 million light-years; 9×1022 metres), and a total mass of the order of 2×1012 solar masses (4×1042 kg). It consists of two collections of galaxies in a “dumbbell” shape: the Milky Way and its satellites form one lobe, and the Andromeda Galaxy and its satellites constitute the other. The two collections are separated by about 800 kpc (3×106 ly; 2×1022 m) and are moving toward one another with a velocity of 123 km/s. The group itself is a part of the larger Virgo Supercluster, which may be a part of the Laniakea Supercluster. The exact number of galaxies in the Local Group is unknown as some are occluded by the Milky Way; however, at least 80 members are known, most of which are dwarf galaxies.
- Class (biology) (Wikipedia)
In biological classification, class (Latin: classis) is a taxonomic rank, as well as a taxonomic unit, a taxon, in that rank. It is a group of related taxonomic orders. Other well-known ranks in descending order of size are life, domain, kingdom, phylum, order, family, genus, and species, with class ranking between phylum and order.