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Nebula
Contained within the confines of our home Galaxy, The
Milky Way, exists areas of vast interstellar gases called Nebulae. These are
designated by categories of Planetary, Reflection, Dark, Emission and Supernova
Remnant. Each category is described below.
| Planetary |
This is the result of ordinary stars that have
turned into Red Giant Stars and then later died. In their death throes
they cast off their external gas layers in violent eruptions. This will
be the eventual fate of our own Sun many millions of years from now. The
name Planetary was coined by early astronomers as the view they were
afforded by their small telescopes reminding them of the planet Saturn.
With the advent of modern telescopes we of course see that these are
some of the most beautiful objects in the Universe. They also contain
the needed ingredients for new star formation. Call it interstellar
recycling. |
| Reflection |
This is resulting from light from nearby
bright stars reflecting off the scattering of dust particles. The nearby
stars are not hot enough to cause ionization of the gas of the nebula
but bright enough to illuminate the dust. Due to the fact wavelengths in
the blue are scattered more readily than red these nebula tend to be of
blue color. |
| Dark |
Similar to reflection nebula except these are
clouds of dust so thick that they block the light from stars that are
behind them. These are often observed with reflection and emission
nebula. |
| Emission |
These are clouds of high temperature gases.
The atoms of these clouds are energized by ultraviolet light emitted
from nearby stars and emitting radiation as they transform into lower
energy states similar to the same way as neon light does. They are most
often red due to the predominant emission line of hydrogen which is red
in color. Other colors are produced by other atoms however hydrogen is
most abundant. These nebula are usually often hot beds for new star
birth. |
| Supernova Remnant |
These are formed as a result of a massive star
ending it's life in a massive explosion or implosion. For a brief few
days the supernova emits as much energy as an entire galaxy. This
process results in a large amount of the star being blown into space
thus forming a supernova remnant nebula. |
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