LECTURE 2 - the sum total of all matter and energy that is...

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LECTURE 2 CHAP 1- What is our Place in the Universe? Star- A large, glowing ball of gas that generates heat and light through nuclear fusion. Planet - a moderately large object that orbits a star Moon (or satellite)- an object that orbits a planet Asteroid- a relatively small and rocky object that orbits a star Comet- a relatively small and icy object that orbits a star Solar (Star) System- a star and all the material that orbits it, including its planets and moons Galaxy- a great island of stars in space, all held together by gravity and orbiting a common center Universe-
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Unformatted text preview: the sum total of all matter and energy; that is everything within the galaxy How can we know what the universe was like in the past? Light travels at a finite speed (300,00 km/s) Moon- light travels 1 second Sun- Light travels 8 minutes Sirius- Light Travels 8 years Andromeda Galaxy- Light travels 2.5 million years Light-year- A The distance light can travel in one year A About 10 trillion km (6 trillion miles) At great distances, we see objects, as they were when the universe was much younger 1 light year = (speed of light) x (1 year)...
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