Galaxies+and+Nebula's

media type="custom" key="4363481"A 'Nebula' is a cloud of gas and dust between stars **
 * THIS PAGE IS BY LIZ WATKINS :)

==== ** What causes the red color? Well, it's sort of like a neon light, but a neon light has neon gas inside the tube, and here the gas giving off the red light is //hydrogen// the simplest and most common element in the Universe. Just like a fluorescent light glows, the energy that causes the hydrogen glow in a nebula is caused from the outside. The nearby stars light up the hydrogen gas. ** ====

==== ** What about the blueish colors? Does it mean that the gas is hot? No. This nebula is not a blackbody, it is giving off light not because it is hot, but because it is //reflecting//. It’s an example of a ‘//reflection nebula’//. Just like our sky is blue, because blue light from the Sun is more likely to bounce around our atmosphere and red light from the Sun is more likely to come through straight (as in a sunset), the blue light from a star in a reflection nebula gets bounced around and spread through out the entire nebula. ** ====

= GALAXIES- HICKSON 44 ↓ = ==**This picture is known as __Galaxy Group Hicksen 44__. It is a group of galaxies instead of a cluster because it has more than two galaxies but less than the hundreds that make up a cluster. The Hicksen 44 Group is 60 million light-years away and is in the constellation of Leo. It contains several spiral galaxies as well as an elliptical galaxy, seen in the upper left. A more famous group of Galaxies is the 'Local Group' of Galaxies which has over 30 galaxies including our own Milky Way, Andromeda, and the Magellanic Clouds. Many galaxies in compact groups like Hicksen 44 are either merging or being gravitaionally pulled apart.**==

__**GALAXY CLUSTERS**__ ==** Galaxies cluster together just as stars cluster together. Clusters range from a few dozen galaxies to several thousand. The galaxies are held in their cluster by gravity. The big cluster of galaxies nearest to us is the Virgo Cluster. Our own galaxy, the Milky Way, is a member of a smaller group of galaxies known as the //Local Group//. It contains three large galaxies and more than 30 smaller galaxies.. The powerful gravity of the big clusters like these attract small groups and individual galaxies and small clusters in their neighborhood. As that happens, the big clusters grow and heat up, which causes them to expand. Astronomers don't know yet whether our Local Group will eventually be swallowed by the Virgo cluster. **==