M45, Pleiades

M45, a portion of the Pleiades open star cluster in the constellation Taurus, at a distance of some 410 light-years. The glow around the stars is interstellar dust which shines by reflected starlight. The entire group is contained within a span of 20 light-years, and is believed to be 20 million years old. KPNO 4-meter Mayall telescope, 1975.