This is a map of galaxies that lie within 20 million light years plotted onto the supergalactic plane. A galaxy is a group of many stars, with gas, dust, and dark matter. The name 'galaxy' is taken from the Greek word galaxia meaning milky, a reference to our own galaxy, the Milky Way.. Galaxy - Galaxy - Types of galaxies: Almost all current systems of galaxy classification are outgrowths of the initial scheme proposed by the American astronomer Edwin Hubble in 1926. The distribution of most of the confirmed Local Group galaxies is shown in the figure below. In Hubble’s scheme, which is based on the optical appearance of galaxy images on photographic plates, galaxies are divided into three general classes: ellipticals, spirals, and irregulars. There is a third spiral galaxy, the Triangulum Galaxy, third biggest galaxy in our group. Local group definition, the group of galaxies, at least 25 of which are known, that includes the Milky Way. Stars are bound together by gravity to form galaxies, galaxies are connected to each other by gravity to form galaxy groups, and galaxy groups are bound together to form galaxy clusters. The Nearest Groups of Galaxies. See more. Recall that stars in the neighborhood of the Sun are typically separated by about 1 parsec . Each large spiral has several smaller galaxies orbiting them. In effect, the expansion of the universe takes place between groups of galaxies, not inside those groups. We don’t know how many galaxies there are in the universe, and we never will, however we do know that we live in a galaxy called the Milky Way. They move towards each other at a speed of 110 km per second (or 400 000 km per hour). Nearly all of the nearby galaxies lie near this plane (the supergalactic coordinate system was originally invented because many nearby galaxy groups lie close to this plane.) Scientists have known for some time that the Milky Way Galaxy is not alone in the Universe. The Milky Way is a spiral galaxy (which will be talked about later) that is part of a large group called the Local Group, which contains dozens of other galaxies. The Local Group is about 3 million light years across with the two large spirals, the Milky Way and Andromeda Galaxy, dominating the two ends.

Gravity holds galaxies together against the general expansion of the universe. The Local Group consists of approximately 50 galaxies; the Andromeda Galaxy and the Milky Way - both spiral galaxies - are the biggest in this group. In the Local Group, galaxies are clearly made up of the light of many individual stars.