English: The galaxy known as M60-UCD1 is located near a massive elliptical galaxy NGC 4649, also called M60, about 54 million light-years from Earth. Packed with an extraordinary number of stars, M60-UCD1 is an "ultra-compact dwarf galaxy." At the time of discovery, it is one of the most massive galaxies of its kind, weighing 200 million times more than our Sun, based on observations with the Keck 10-meter telescope in Hawaii. Remarkably, about half of this mass is found within a radius of only about 80 light-years. This would make the density of stars about 15,000 times greater than found in Earth's neighborhood in the Milky Way, meaning that the stars are about 25 times closer.