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