Milky Way…….More than just a candy bar! p. 234 or WB 149 Galaxies Milky Way…….More than just a candy bar! p. 234 or WB 149

Distance Measurement in Space No miles. Too small. Astronomical Unit Average distance bt. Earth and Sun. (93 million miles)

Light YouTube Clip 1AU=8.3 light min. We use this to measure distance. light year-outside S.S. light minute or second-inside S.S.

What is a galaxy? A galaxy is a group of stars, gas, and dust that are held together by gravity.

Edwin Hubble Began to classify galaxies in the 1920s. The Hubble Space Telescope is named after him.

Types of galaxies 1.Elliptical 2.Spiral 3.Irregular

Elliptical Galaxy Many look like a giant sphere or a star football. 1/3 of all galaxies are elliptical. They have very bright centers. This one is called ESO 325-G004.

Spiral Galaxy These look like a pinwheel. They have a bulge in the center and spiral arms. This one is called Messier 101 or NGC 5457.

Irregular Galaxy When Hubble began to classify galaxies he had a group of leftovers. They were called Irregulars. This one is called NGC1427A.

Our Galaxy: The Milky Way! 100,000 light years in diameter and 1,000 light years thick. Anywhere from 200 billion to 400 billion stars. Galaxy = 80 miles Earth = .08 inches

THE END!! NGC 4414