Andromeda Galaxy A massive spiral million light-years away, over twice the diameter of our own Milky Way, it's the largest nearby galaxy. Andromeda's population of bright young blue stars lie along its sweeping spiral arms. by Spitzer Space Telescope
A nebula from Latin: "cloud"is an interstellar cloud of dust, hydrogen, helium and other ionized gases. Originally, nebula was a name for any diffuse astronomical object, including galaxies beyond the Milky Way.
Hubble Captures View of 'Mystic Mountain' the Carina Nebula. The top of a three-light-year tall pillar of cool hydrogen is being worn away by the radiation of nearby stars, while stars within the pillar unleash jets of gas that stream from the peaks.
NGC the Iris Nebula. W/in the Iris, dusty nebular material sur-rounds a hot, young star. The dom-inant color of the brighter reflection nebula is blue, characteristic of dust grains reflecting starlight.