Astr111 Photography Projects, Fall 2009

Messier 74- Spiral Galaxy, Ally Hopp

There are three types of galaxies: spiral, elliptical and irregular. M74 happens to be a spiral galaxy. Spiral galaxies are galaxies that look like a flat, white disk with a central yellow bulge. Outside the bulge is the disk, which is filled with gas and stars. Stars sometimes cluster to form branches coming off the central bulge, also called spiral arms. Spiral arms are masses of interstellar material and young stars that wind out in a plane from the central nucleus of a spiral galaxy. Scientists guess that this kind of galaxy was formed when the universe was very young. Hydrogen and helium gas filled up outer space unevenly, and through expansion and forces of gravity, different galaxies' expansion stopped and reversed which formed protogalactic clouds. These protogalactic clouds eventually turned into galaxies like the one you see above.

Messier 74 clearly has a central yellowish bulge, as well as major spiral arms. It's linear size is 77070.8 lightyears, and it is 35 million light years away from the earth.The particularly bright spots are simply stars in the foreground. If you closely look at this galaxy, you'll notice a blueish hue around the edge of the outer spiral arms, which is the color that appears upon the birth of new stars.

References:

Bennett, Jeffrey, Megan Donahue, Nicholas Schneider, and Mark Voit. The Cosmic Perspective. 3rd ed. San Francisco: Pearson Education, 2004. 653-54. Print.