# 2 - Speed of Light-light can travel very fast 3x10^8 meters...

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It is visible every night because it is above the north pole of earth. Also called the North Star it and can be used to find which way is north. It is not a very bright star. Rising and Setting Stars (Earths rotation) -the earth eastward rotation causes stars to appear to move westward. -Polaris, the North Star, doesn’t move -Stars near the Polaris move in small circles -Stars far from Polaris move in long arcs. The stars in a constellation are not close in space In fact, the stars slowly move through space. Many years from now, the constellation will look different! Distances to Stars -stars were once thought to be fixed in a dome above the earth -We now know that the stars are scattered through space at great distances. -The nearest stars are located about 10 trillion miles away. (10,000,000,000,000 miles) -astronomers measure huge distances using a special units. = light year

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Unformatted text preview: Speed of Light-light can travel very fast: 3x10^8 meters per second (m/s)-That’s 186,000 miles per second!-Even at this speed, light takes years to travel between the stars.-The distance light can travel in 1 year is called Light Year . (l.y.)-One light year = 1 x 10^16 meters Light Years-Light-Year is a unit of distance-a light-second is the distance light travels in one second. =186k miles-the sun is 8 light-minutes away-the nearest star to the sun is 4 light years away-the nearest galaxy is 2 million light-years away. Looking Back in Time-although light travels fast, it does not move instantaneously.-for example star Rigel (in orion) is 800 light years away.-it takes light from rigel 800 years to reach us.-so we see Rigel as it was 800 years ago!-we see the closest galaxy (Andromeda) as it was 2 million years ago. Betelgeuse: 640 light years...
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2 - Speed of Light-light can travel very fast 3x10^8 meters...

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