Milky Way. Optical image of our galaxy, the Milky Way, in the constellation of Aquila the Eagle. The brightest star in Aquila is Altair (lower left). The Milky Way is a luminous band in the sky caused by the light of stars which are too numerous to be seen indivi-dually. The stars are numerous because an observer looking in their direction is viewing along the plane of our galaxy's disk. The dark lane in the Milky Way, called the Great Rift, runs from upper left to top right. The darkness of the Great Rift is caused by huge clouds of interstellar dust which block the light from the more distant stars.