Nebulas (Star-Forming, Reflection, Planetary, Supernova, Dark)
Nebulas are giant masses of cloud and dust, they can be light years across such as the Snake Nebula which is a 3 light years across. There are five types or to put it another way, classifications of Nebulas out there, they are HII, reflection, planetary, supernova remnants and dark. These objects of gas can mark the beginnings of or end of Stars and both. Let me explain, when a star dies, its materials of whats left of it can do onto recreate a new start somewhere. Whilst most nebulas are invisible to the naked eye, it is possible to just about see the Orion Nebula. The names that Nebulas are given because they look similar to real life objects, the Witch Head Nebula as seen below is because it looks vaguely like a witches head. The correct plural of nebula is nebulae. It is a common mistake to make, made on many ocassions.
HII Star Forming Nebula
|These large nebula areas of gas and dust are collapsing to form new stars. A long time ago, more than 5 billion years ago, this area of space would probably have been a nebula before it collapsed and formed The Sun and the planets and also me and you. The Eagle Nebula in the constellation of Serpens is an example of where stars are being formed. The process to a fully fledged star system will take many millions or even billions of years before it becomes a solar system like ours.|
|A reflection nebula is one which is being seen because the light from behind the nebula, sometimes another nebula is being relfected so that we can see it. The Witch Head Nebula is a Reflecton Nebula, it is reflecting light off Rigel, a nearby star. The star lies about 800 light years away and is about 50 light years across. 1. They tend to be blue in nature because dust that causes their light tends to be more efficiently reflected2. |
|Despite its name, planetary nebulae aren`t anything to do with planets. They get their name from the British astronomer William Herschel, Sir who when he first saw a planetary nebula, he thought it looks like Uranus. Planetary Nebulae are created when a star comes to the end of its life. When the star collapses, it might not explode like a supernova but expand and die like the Ring Nebula in the constellaton of Lyra. The Ring Nebula and a lot of others will contain a white dwarf at the centre.|
|When a star supernovas, it can create a nebula which is similar to the planetary nebula above. The difference can be explained by the type of star that produced the explosion. With a Supernova Remnant, the star that would produce the explosion would be about 8 or more times our son. Anything smaller would create a planetary nebula. 3. The image is of the Crab Nebula, which despite its name is not in Cancer but is in Taurus. |
|The Dark Nebula is so dark and dense that light can not get through. The most well known example of a dark nebula is the Horse Head nebula in the constellation of Orion. Although when you look at the horse head images, you will often see the horse head as a standalone nebula but it is in fact, part of a much larger nebula as the picture besides shows you the whole picture.|