The legendary Hubble Space Telescope, orbiting Earth, peered inward and captured a vivid image of stars near the center of the Milky Way, a galaxy that's some 100,000 light-years across (or about 1,000,000,000,000,000,000 kilometers).

That dense group of stars is called a "globular cluster," and that's specifically "globular cluster ESO 520-21," found near the center of the galaxy.