Emission Nebula & H II Regions

Written by on December 14, 2009 in Learning with 0 Comments


An emission nebula is a cloud of ionized gas that emits various colours of light. There are several different types of emission nebulae; the variety illustrated here is called an H II region.

An H II region is a cloud of Hydrogen gas that gives birth to new stars. These young, hot, blue stars shine with a tremendous amount of ultraviolet light. Like flashlights in a fog, a cluster of stars can work together to illuminate an enormous region of space, one that can stretch for hundreds of light years.

An example of an emission nebula you can see with your own eyes in the Orion Nebula. On a dark clear night you can see the glowing areas of gas around the stars that form its central region.

A nebula’s colour depends on its chemical composition and the level of ionization. Hydrogen glows a reddish colour when ionized and if enough energy is available, blues and greens may also emerge from other elements. These elements can include: Helium, oxygen, nitrogen.

Some nebulae also have dark regions stirred through them.  These are clouds of dust that block the light and cause oddly shaped silhouettes to be scattered through the structure. The combination of emission nebula and dust clouds can produce some very beautiful objects in the night sky.

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