Scale of the Universe and Constellations

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# Scale of the Universe and Constellations - PowerPoint PPT Presentation

Scale of the Universe and Constellations. Mrs. Breeding 6 th Grade. Light Years. The fastest thing that we know of is light which travels at a speed of 186,000 miles per second in empty space .

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Presentation Transcript
Light Years
• The fastest thing that we know of is light which travels at a speed of 186,000 miles per second in empty space.
• To get an idea of how fast this is, light can travel about seven times around Earth in one second!
• Astronomers use the speed of light to measure how far away things are in space.
• A light-year is the distance that light can travel in one year. Astronomers use light years to measure distance between stars.
• In one year, light travels about 5,880,000,000,000 miles.
• So, this distance is 1 light-year. For example, the nearest star to us is about 4.3 light-years away.
• Our galaxy, the Milky Way, is about 150,000 light-years across.
Astronomical Unit
• A measurement used to determine distances in our Solar System. One AU (Astronomical Unit) is defined as the distance from the sun to the Earth.
• 1 AU= 93 million miles
• Most scientist use AU’s to measure approximate distances between planets.
Galaxies
• Galaxies are made up of millions of stars and solar systems.
• Our solar system is very tiny compared to the milky way galaxy.
• As big as the milky way galaxy is, it is very small when compared to the universe.
• Most of the Universe is empty space.
Constellations
• “Patterns in the night sky.”
• Because Earth revolves around the sun, the positions of the constellations appear to change throughout the year.
• Early Astronmers thought that galaxies were single stars because they are so far away.
• Stars in a constellation look like they are the same distance from Earth but, they aren’t. They are just the same general direction from Earth.
• Ancient people named the constellations.
• As Earth travels in its orbit different constellations are visible at different times of the year.
Little Dipper
• Polaris- (North Star) which was used to guide ancient people as they traveled. Is part of the Little Dipper.
• Part of the constellation called Ursa Minor.
Big Dipper
• The Big Dipper is part of a larger constellation called Ursa Major.
Orion
• Orion is clearly visible in the night sky from November to February. Orion is in the southwest sky if you are in the Northern Hemisphere or the northwestern sky if you are in the Southern Hemisphere.
• The belt is easy to see.