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GALAXIES

GALAXIES. From: Jim Lochner, USRA & NASA/GSFC. What is a Galaxy ?. Solar System. Distance from Earth to Sun = 93,000,000 miles = 8 light-minutes. Size of Solar System = 5.5 light-hours. What is a Galaxy?. Stellar Region. Sun (solar system too small to be

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GALAXIES

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  1. GALAXIES From: Jim Lochner, USRA & NASA/GSFC

  2. What is a Galaxy ? Solar System Distance from Earth to Sun = 93,000,000 miles = 8 light-minutes Size of Solar System = 5.5 light-hours

  3. What is a Galaxy? Stellar Region Sun (solar system too small to be seen on this scale) 30 light-years

  4. What is a Galaxy? A galaxy Is a massive collection of stars, gas, and dust kept together by gravity Our galaxy is the “Milky Way” Sun’s Stellar Region 200,000 light-years

  5. What is a Galaxy? If our solar system was the size of a cell in the human body, then our galaxy would still measure over one mile across.

  6. What is a Galaxy? • The largest galaxies contain more than a trillion stars. • Smaller ones have only a few million. • Astronomers don’t count the stars, but estimate how many stars a galaxy might have.

  7. disk-like appearance with arms of stars and dust forming a spiral pattern similar to spirals but with a bright bar of stars and gas through the center elliptically-shaped, with less gas and dust than spirals; no disk or “arms” neither elliptical nor spiral in shape; gas and dust as in spirals but no defined “arms” distorted form of one of the above types, often due to collision with another galaxy or similar catastrophic event Types of Galaxies Spiral Barred Spiral Elliptical Irregular Peculiar

  8. Types of Galaxies Quiz ? A B C D E

  9. Galaxy Formation According to the Big Bang theory, galaxies began when large clouds of gas and dust collapse as a result of their gravity. As the cloud shrinks and the debris is compacted, stars and planets form.

  10. Contents of Galaxies Gas Clouds The Latin word for “cloud” is nebula. In space nebulas (or nebulae) are giant clouds of gas and dust.

  11. Contents of Galaxies Open Cluster Small group of new stars that formed at the same time from a cloud of gas and dust.

  12. Contents of Galaxies • Globular Clusters • A spherical bundle of older stars that orbit a galaxy as a satellite. They are very tightly gravitationally bound, which gives them their spherical shape and dense inner core of stars. • .

  13. Spirals vs. Ellipticals • Finally the type of galaxy depends on initial rate of star formation: • - If stars form quickly, then galaxy becomes elliptical. Stars form within initial distribution of gas,and follow their initial orbits. • - If stars form later, the gas has time to collapse into a disk. Most stars from within the disk. The galaxy becomes a spiral.

  14. Formation via Galaxy Mergers • In clusters, galaxies can pass close to one another. • Galaxies can become distorted, and often merge. • Mergers often lead to giant elliptical galaxies at the heart of large clusters.

  15. Spirals in Grazing Encounter

  16. Antennae Galaxies

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