Galaxies

Â Â Â Galaxies are large gravitationally bound groups of stars, gas, and dust. The Milky Way is an example of a galaxy and our sun is just one of trillions of stars in it. Galaxies are among the largest structures in the universe. With the exception of the our galactic neighbor, the Andromeda Galaxy (and a few others), Galaxies are much too distant to be seen by the unaided human eye.Â

Â Â Â When we view Galaxies we are looking into the distant past. Light can travel about 186,000 miles per second and 5,865,696,000,000 miles per year, but galaxies are much much further away than that. Therefore, it takes millions and sometimes even billions of years for the light from galaxies to reach earth. The light that we receive would have been released in the distant past, and when we observe it, we are seeing what the galaxy looked like eons ago.

Â Â Â There are many Different classifications of Galaxies. The main types are Spiral, Elliptical and Irregular. Spiral Galaxies are generally younger, and blue in color due to star formation. Elliptical Galaxies are older, redder, and devoid of star formation. Irregular Galaxies are just that, Irregular. They are called irregular because they don't resemble any other galaxy type. Usually they contain blue star forming regions and lots of interstellar dust.