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17 Cards in this Set
- Front
- Back
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Kepler's 1st Law
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1. All planets travel around the sun in elliptical orbits with the sun at one of the focus points.
2. An ellipse is a slightly oval shape. 3. The distance between a planet and the sun changes as planets do not orbit the sun in perfect circles. |
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Perihelion
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January 2nd-when we are closest to the sun.
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Aphelion
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July 4th-when we are furthest from the sun.
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What causes the seasons?
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The cause of the seasons is NOT due to the Earth's distance from the sun-it is due to the earth's tilt. This is why it seems odd that on Jan 2nd (although it is cold) the Earth is closest to the sun and on July 4th (although it is warm) we would be furthest from the sun.
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What objects orbit in an ellipse?
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All planets orbit in an ellipse. The moon orbits the earth in an ellipse. Comets & asteroids orbit the sun in ellipses as well.
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Kepler's 2nd Law
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1. Each planet moves around the sun in such a way that an imaginary line drawn from the planet to the sun will sweep over equal areas in equal times.
2. The closer a planet is to the sun, the faster it travels. 3. Earth travels faster in January. 4. Earth travels slower in July. |
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The Terrestrial Planets
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1. Mercury, Venus, Earth, Mars.
2. Small, rocky, thin atmospere. 3. A spacecraft could be landed on these planets. 4. Rotate slowly. 5. Revolve around the sun quickly. 6. few moons 7. warmer planets in our Solar System 8. closer to the sun |
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What is the average distance from the earth to the sun?
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150 million km (93 million miles)
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Why would it take Mars longer to orbit the sun than the Earth?
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1. Mars is further away from the sun than the earth is, so it travels slower. Also, as it is further away, the trip around the sun would be a longer journey.
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What is the average speed of the earth as it moves through its orbit?
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18 miles/second
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Why is our summer longer than our winter?
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There are 3 more days in the summer because in the summer we are furthest from the sun. Because of this we take longer to get through orbit.
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Kepler's 3rd Law
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Called "The Harmonic Law". It shows a mathematical relationship between the period (time needed to orbit the sun) of a planet and its distance from the sun.
P = D P= amount of time it takes to the orbit sun, measured in years D= distance from the sun, measured in AU's |
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If you wish to know how long a planet will take to orbit the sun, what must you know 1st?
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The distance of the planet from the sun.
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How long would it take a planet to orbit the sun if it was 900,000,000 km from the sun?
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Step 1:
900,000,000 km (D) 150,000,000 km (1 AU) Step 2: 900 150 Step 3: P = D P = (6) Step 4: P = 216 Step 5: P = 216 Step 6: P = 14.7 yrs |
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Isaac Newton (about 1670)
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1. He discovered Gravity
2. All objects have gravity, the amount depends on a) mass of the object b) the density of the object 3.Objects with more mass/density will have more gravity 4. Strength of attraction between 2 objects depends on a) the strength of each object's gravity b) the distance between the objects. 5. Stronger attraction exists between objects closer together, less attraction as objects move further apart. 6. Known as Newton's "Universal Law of Gravitation" |
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The Jovian Planets
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1. Jupiter, Saturn, Uranus, Neptune
2. very large 3. made mostly of gas 4. impossible to land a spacecraft here. 5. no solid surface, thick atmosphere, crushing pressure 6. numerous moons 7. farthest from the sun 8. coldest planets in the Solar System |
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How long would it take a planet to orbit the sun if it was 900,000,000 km from the sun?
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Step 1:
900,000,000 km (D) 150,000,000 km (1 AU) Step 2: 900 = 6 AU 500 Step 3: P = D P = (6) Step 4: P = 216 Step 5: P = 216 Step 6: P = 14.7 yrs |
