An all-sky view of stars in the Milky Way and neighboring galaxies, based on the first year of observations from the European Space Agency's Gaia satellite. This map shows the density of stars observed by Gaia in each portion of the sky. Brighter regions indicate denser concentrations of stars, while darker regions correspond to patches of the sky where fewer stars are observed. The Milky Way is a spiral galaxy, with most of its stars residing in a disc about 100,000 light-years across and about 1000 light-years thick. This structure is visible in the sky as the Galactic Plane, the brightest portion of this image which runs horizontally and is especially bright at the center. Darker regions across the Galactic Plane correspond to dense clouds of interstellar gas and dust that absorb starlight along the line of sight. Many globular and open clusters are visible in the image. Globular clusters, large assemblies of hundreds of thousands to millions of old stars, are mainly found in the halo of the Milky Way, a roughly spherical structure with a radius of about 100,000 light-years. Open clusters are smaller assemblies of hundreds to thousands of stars and are found mainly in the Galactic Plane. The two bright objects in the lower right of the image are the Large and Small Magellanic Clouds, two dwarf galaxies orbiting the Milky Way. Other nearby galaxies are also visible, most notably Andromeda, and its satellite, the Triangulum galaxy.