The largest constellation of the zodiac, and the second-largest constellation of all, representing the goddess of justice. It lies on the celestial equator. The Sun passes through Virgo from the third week of September to the end of October, and hence lies within the constellation at the autumnal equinox. Its brightest star is Spica (Alpha Virginis). Gamma Virginis is a double star known as Porrima. The constellation contains numerous members of the Virgo Cluster of galaxies. M104, the Sombrero Galaxy, is not part of the cluster. Virgo also contains the brightest quasar, 3C 273, magnitude 12.9, about 3 billion l.y. away.