Galaxies

Astronomy Night 2013By Lauren Farnworth

Team 7A Mr. Reed

What are Galaxies?

A galaxy is a large system of stars held together by mutual gravitation and

isolated from similar systems by vast regions of space.

How Many Galaxies are There?

NASA estimated in 1999 that there were 125 billion galaxies in the known Universe.

How Do We Receive Information and Pictures About Galaxies?

The way we receive high pixel pictures and information about galaxies is through the Hubble Telescope. The Hubble Telescope is a space telescope that was carried into orbit by a Space Shuttle in1990. It still remains in operation and gets us some of the most high quality and in depth pictures of galaxies.

Some of Hubble’s pictures.This is a picture of what the images were like before and after Hubble.

Do We Live in a Galaxy?

We actually do, we live in the Milky Way Galaxy. The Milky Way Galaxy is 100,000-120,000 light years across which means it probably contains about 100-400 billion stars. The Solar System is located within the disk, about 27,000 light-years away from the Galatic Center. 

Are All Galaxies the Same Shape?

Not exactly. There are four most common galaxy shapes. These are spiral, elliptical, lenticular, and irregular. Our Milky Way is a perfect example of a spiral galaxy. A spiral galaxy looks like a pinwheel. It is basically the nucleus with its different “arms” spiraling outwards. One interesting fact about spiral galaxies is that young stars are formed in the outer arms while older stars are found near the center.

Elliptical and Lenticular Galaxies.

The next two types of galaxies are elliptical and lenticular shaped galaxies. These types are the kinds that are the most similar. They have few or no dust lanes and have mostly older stars. Of the four galaxy shapes this is the most organized.

Irregular Galaxies.

Irregulars have an indeterminate shape. These galaxies are often small and don’t have enough gravitational force to organize into a more regular form. The Hubble telescope has taken images of famous irregular galaxies like the Magellanic Clouds.

Thanks for Watching!