2.+Nebula


 * __Nebula:__**

__**Description:**__ Nebula is the Latin word for "cloud" and it's made up of dust, hydrogen and **plasma**, mostly of hydrogen. Nebula was a name for any astronomical object further more than the Milky Way, also, Nebula are clouds formed after a star explodes.Furthermore, the formations of gas, dust and other materials wondering in space would be combine together to form larger masses, which attract further matter due to that dust and gas would wonder around space and would be attracted, and eventually will become big enough to form stars. There are many types of nebula's such as; -__**planetary nebula**__: a shell of gas expelled from certain kinds of extremely hot stars such as red giant's or red supergiants.

__**-emission nebula**__: " An emission nebula is a nebula that glows (it emits light energy). The reddish light is produced when electrons and protons combine, forming hydrogen atoms. **Emission** nebulae are formed when energetic ultraviolet light from a very hot star excites a cloud of hydrogen gas; the UV radiation **ionizes** the hydrogen (it strips electrons from the hydrogen atms). The free electrons combine with protons, forming hydrogen and red light" ( Enchanted Learning 1999-2009)

__**-reflection nebula:**__ glows because the dust in it reflects the light from nearby stars. __**-ring nebula:**__ huge cloud of dust and gases which shape like a ring

There are many well known nebula's such as the crab nebula, cygnus loop, eagle nebula, horsehead nebula, orion nebula. The video below shows some of these nebula's. media type="youtube" key="P-QcTOjLaKc" height="344" width="425"

__**Habitability:**__ Nebula couldn't be inhabited by humans as its a gas planet and does not have oxygen, also humans could not survive without oxygen also there are no traces of water, and these to things are essential to human life, therefore without this life is not possible in a nebula.

Without the oxygen and water humans cannot survive therefore there is no possibility of life being sustained on a nebula.
 * __Justification:__**

Plasma:** a fourth state of matter
 * __Glossary:__
 * Emission:** discharge
 * Ionizes:** the act of converting


 * Go to bibliography for emission nebula direct quote source