About 145 light-years in diameter, M13 is composed of several hundred thousand stars, the brightest of which is a red giant, the variable star V11, also known as V1554 Herculis, with an apparent visual magnitude of 11.95. M13 is 22,200–25,000 light-years away from Earth, and the globular cluster is one of over one hundred that orbit the center of the Milky Way.