Nebula Facts

Nebula Facts
A nebula is a very massive cloud made up of dust, gas, plasma, and hydrogen. Nebulae are also considered nurseries as this is where stars are created, or born. Nebula is the Latin word for cloud, and until the 1920s distant galaxies were also referred to as nebulae as well. The first true nebula recorded was mentioned in the 964 book titled Book of Fixed Stars written by Abd al-Rahman al-Sufi - a Persian astronomer. The Orion Nebula was discovered in 1610 by Nicolas-Claude Fabri de Peiresc. There are different ways in which nebulae can form. Some form as a result of supernova explosions, or from gas already in the interstellar medium, while others are created by stars.
Interesting Nebula Facts:
An emission nebula is formed when ionized gases emit a variety of colors, most often the result of a nearby hot star. An example of an emission nebula is the Omega Nebula.
A dark nebula is so dense that objects behind are obscured. This type of nebula extinguishes light with interstellar dust grains. An example of a dark nebula is the Horsehead Nebula.
A planetary nebula is a type of emission nebula that is made up of glowing and expanding ionized gases. An example of a planetary nebula is the Cat's Eye Nebula.
A protoplanetary nebula is a type of reflection nebula that exists during the evolution of a star between the asymptotic giant branch phase and planetary nebula phase. An example of a protoplanetary nebula is the Red Rectangle Nebula.
A diffuse nebula is one that does not have well-defined boundaries. An example of a diffuse nebula is the Carina Nebula.
A reflection nebula looks blue because it is not able to emit its own light and reflects the color of stars nearby. If a reflection nebula exists it means that an emission nebula is close by.
Examples of particularly well-known nebula include Ant Nebula, Eagle Nebula, Hourglass Nebula, Barnard's Loop, Boomerang Nebula, Crab Nebula, Eskimo Nebula, Fox Fur Nebula, Lagoon Nebula, Pelican Nebula, Orion Nebula, and Tarantula Nebula.
There are catalogues of existing nebula including Gum Catalogue, RCW Catalogue, Sharpless Catalogue, and Caldwell Catalogue.
Nebulae are usually very vast, reaching a diameter as wide as millions of light years.
A light year is the distance that light is able to travel in one year.
Some nebulae are named for their shape, such as the Horsehead Nebula, which looks like a horse's head when viewed from earth.
The Hourglass Nebula looks like an hourglass and is located roughly 8,000 light-years from earth.
Scientists have a theory that new stars are created in nebulae. The idea is that the gas and dust in the nebula begins to squash together and contract, getting hotter and denser. Once this cloud becomes hot and dense enough it ignites the hydrogen it contains and a new star is created.
It is estimated that in approximately five billion years the sun will become a nebula.
Any nebulae that are located beyond the Milky Way are referred to as extra-galactic nebulae.

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