# Day 1 - Each of the above differs from the next by a factor...

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August 31: Plan for the class Introductions Skywatch Syllabus What is Astronomy? Using Powers of 10 o What is a light year? o Where are we in the Universe? Skywatch Point out something cool in the sky o So you know what’s visible We began the semester with Venus being visible o So you “look up” o So you can impress your friends Reinforce a term or concept Introduce a term or concept Review for test Powers of Ten 10 1 = 10 (to the 1 has 1 zero) 10 2 = 100 (to the 2 has 2 zeros) 10 3 = 1000 10 0 = 1 10 -1 = 10 -2 = Light Year Distance light travels in a year “When will we get there” problem o Distance = velocity * time o Velocity of light = 3 * 10(to the)5 km/s = c o 1 year = 3.16 * 10(to the)7 seconds o D = (3 * 10(to the)5 km/s) * (3.16 * 10(to the)7 s) o D = 9.5 * 10(to the)12 kilometers (About 6 trillion miles!) What’s the big deal? 10 6 = million 1,000,000 10 9 = billion 1,000,000,000 10 12 = trillion 1,000,000,000,000

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Unformatted text preview: Each of the above differs from the next by a factor of 1,000. From the Powers of 10 video: these go in the order of smallest to largest • Planetary System o We started with the earth and as we backed away we saw star(s), planets, minor bodies help by gravity o Our Solar System: Sun, 8 planets with moons, dwarf planets, comets, asteroids • Galaxy o Collection of stars (some starts have planets and are planetary systems), gas, dust help by gravity o Our Milky Way galaxy contains about 400 billion stars • Universe o Galaxies distributed in clusters held by gravity o About 100 billion galaxies Pluto shares its orbit with many icy bodies. It hasn’t “cleared” its orbit and that is why it has been demoted. Our MILKY WAY GALAXY We live in an immense universe comprised of billions of galaxies. Each galaxy contains billions of stars and many stars have planets....
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Day 1 - Each of the above differs from the next by a factor...

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