Galaxy is a very large system, consisting of stars and interstellar matter. Usually contain several trillion trillion stars, with masses between a few million to several trillion times that of our Sun. With an area of several thousand to 100,000 light years. They have a variety of shapes: spiral, lenticular, elliptical and irregular. Besides simple stars, they usually contain various types of star clusters and nebulae. We live in a giant spiral galaxy, the Milky Way, with a diameter of 100,000 light-years away and our sun as one of about 100 billion stars in the Milky Way galaxy.
Only three galaxies outside the Milky Way visible to the naked eye. The people in the northern hemisphere can see the Andromeda Galaxy, which is about 2 million light-years away. The people in the southern hemisphere can see the Large Magellanic Cloud, which is about 160,000 light-years from Earth, and the Small Magellanic Cloud, which is about 180,000 light years.
Galaxies are not distributed uniformly in space. Some do not have close neighbors, but some are in pairs, with each orbit to another. But most of them are found in groups called clusters. A group of galaxies may consist of a few dozen to several thousand galaxies. With a diameter of roughly 10 million light-years away.
Clusters of galaxies, in turn, are grouped into larger structures called superclusters. On a larger scale, galaxies are arranged in a large network. Interconnected network consisting of strings or filaments of galaxies around the relatively empty regions known as voids. One of the largest ever mapped the network structure is known as the galactic Great Wall. This structure is more than 500 million light-years long and 200 million light-years wide.
