Created 26-Mar-10
Modified 12-Aug-16
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Emission, reflection and dark nebulaes are areas of a galaxy where stars are formed from molecular hydrogen (HII). The Milky Way is littered with dust and an abundance of HII.
Emission nebula glow red because of an HII region becoming ionized by nearby stars. The electons "freed" by this ionization are continually absorbed and reemitted causing it to glow red.
Dark nebulas are cool clouds of dust and molecular hydrogen that can be seen when silhouetted against a bright background (ie. the Horsehead nebula).
Reflection nebula are areas in which material that contain dust is reflected from nearby stars. Because of the shorter wavelength of light this "dusty" area appear blue.
Stars are formed when molecular hydrogen accretes, or falls into itself, gradually increasing in gravity until it reaches a certain mass. As this material continues to fall into itself the temperature and pressure increases until nuclear fusion begins and a star is formed.

M8, M20 and M21 the Lagoon nebula, Trifid nebula and an Open cluster

M8, M20 and M21  the Lagoon nebula, Trifid nebula and an Open cluster

NGC 7000 North America nebula

NGC 7000 North America nebula

NGC 7000 North America nebula and IC 5070 Pelican nebula

NGC 7000 North America nebula and IC 5070 Pelican nebula

NGC 1027 the Heart and Soul nebula

NGC 1027 the Heart and Soul nebula

NGC 1499 California nebula

NGC 1499 California nebula

the Rosette nebula

the Rosette nebula

the Horsehead and Orion nebula

the Horsehead and Orion nebula

NGC 2359 Thor's Helmet

NGC 2359 Thor's Helmet

M16 the Eagle nebula

M16 the Eagle nebula

M16 the Pillars of Creation

M16 the Pillars of Creation

M8 the Lagoon nebula

M8 the Lagoon nebula

Barnard 33 the Horsehead nebula

Barnard 33 the Horsehead nebula

NGC 281 the Pac Man nebula

NGC 281 the Pac Man nebula

IC 1848 the Soul nebula

IC 1848 the Soul nebula

IC1805 the Heart nebula

IC1805 the Heart nebula

NGC 1499 the California nebula

NGC 1499 the California nebula

IC410 the Tadpoles

IC410 the Tadpoles

IC 405 the Flaming Star nebula

IC 405 the Flaming Star nebula

NGC 2264 the Cone and Fox Fur nebula

NGC 2264 the Cone and Fox Fur nebula

NGC 7635 the Bubble nebula

NGC 7635 the Bubble nebula