Hercules, constellation in the northern sky at about 17 hours right ascension and 30° north in declination. Its brightest star is Beta Herculis, with a magnitude of 2.8. Hercules contains the solar apex, the point on the sky toward which the Sun is moving as it orbits in the Milky Way Galaxy, and M13, one of the brightest globular clusters. To early Greek astronomers such as Eudoxus and Hipparchus, this constellation was known as Engonasin, Greek for “the kneeling man.” It was not until the 2nd century bce that the identification was made with the Greek hero Heracles.