Reflections Of

Today's Astronomy Picture of the Day is of reflection nebula IC 4592 in the constellation of Scorpius. The Blue Horsehead (not the Horsehead in Orion) is made up of dust and reflects the light of nearby stars (hence, the blue color, thanks to nearby Nu Scorpii). Another class of nebula is the emission nebula (where the gas glows thanks to energy imparted from an outside source), of which The Great Nebula of Orion is a good (and spectacular, in this photo) example.