IN A WORLD FAR, FAR, AWAY……

GALAXIES

The Milky Way galaxy is brighter in the summer because you are looking The area of the sky that this picture was taken from equaled the size of the President’s eye on a dime held at an arm’s length! If the galaxy is red, it is and old one. If the galaxy is blue it is a new galaxy The Milky Way galaxy is brighter in the summer because you are looking toward the center of the galaxy, where as in the winter you are looking out through the outer arm, [called the Orion arm}.

Older stars are in the nuclear bulge and the outer edge. Younger stars are in the spiral arms of the galaxy. Distance of our Solar System from the Galactic Center is 25,000 to 27,000 light years. Galaxies rotate at the speed of 220 km per second or 136.7 per second. Our Sun takes 240 million years to rotate around the Galaxy. Galileo was the first to discover that the Milky Way was made up of millions of stars. He did not realize that our galaxy was one of millions of galaxy in our universe. contains gas & dust 32,000 light years center of the galaxy The region from the nuclear bulge to the edge. 1500 to 2000 light years thick. The entire Galaxy is contained within this area. Halo diameter is 130,000 light years.

Our Universe contains billions of galaxies and each galaxy contains billions of stars. Galaxies are large groups of stars that move together through space. Galaxies can be based upon their shape.

Galaxies rotate because of gravitational influences and are flattened into their shape. They begin as elliptical galaxies and flatten out into spiral or barred spiral galaxies. Because of this spinning away from the center of the galaxy, the stars appear to move away from the middle. This is known as the red shift.

GALAXY TYPES SPIRAL IRREGULAR ELLIPTICAL Early stage of galaxy formations. Lack gas and dust. More uniform in shape. 15% of galaxies are this one. No distinctive shape. Break up of galaxy. 3% of galaxies are this one. NORMAL BARRED Middle stage of galaxy. Flattening out from elliptical stage. Most galaxies are this one.

ELLIPITICAL GALAXY Shaped like a football. Largest known galaxy type. M33 R.A. 1h 31m Dec. 30.24 Contains mostly older stars that have bright centers and little gas.

Normal Spiral Arms come from the center of the galaxy. The arms are due to the rotation of the gravity. M74 R.A. 1h 34m Dec. 15.32 Whirlpool Galaxy M51 R.A. 12h 37m Dec. -11.21 Andromeda Galaxy M31 RA. 0h 40m Dec. 41 The Milky Way was thought to be a normal spiral galaxy. It is located in the Local Group which is a cluster of galaxies.

BARRED SPIRAL Appears to have a bar across the center of the galaxy. Scientist now think the Milky Way may be this type, due to recent evidence. M83 R.A. 13h 34m Dec. -29.37 M104 Sombrero Galaxy R.A. 12h 37m Dec. -11.21

IRREGULAR GALAXY M82 R.A. 9 h 51m Dec. 69.56 No specific shape Breaking up of galaxy. Have close companions of large’ spiral galaxies. Gravity distorts the shape. M82 R.A. 9 h 51m Dec. 69.56

GALAXIES COLLIDING The universe is expanding and causing two galaxies to form into one. Our galaxy, the Milky Way, is a combination of two galaxies. The Milky Way and the Andromeda Galaxy will eventually collide in a billion years.