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Kepler’s Laws. Kepler’s Laws. Johannes Kepler Mars’ orbit is not a perfect circle, it is elliptical The speed of Mars’ orbit changes Closer to sun = faster Farther away from sun = slower Lead to Kepler’s 3 Laws. Kepler’s 1 st Law.
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Kepler’s Laws • Johannes Kepler • Mars’ orbit is not a perfect circle, it is elliptical • The speed of Mars’ orbit changes • Closer to sun = faster • Farther away from sun = slower • Lead to Kepler’s 3 Laws
Kepler’s 1st Law • The path of each planet around the sun is an ellipse with the sun at one focus
Kepler’s 2nd Law • Each planet revolves so that the “imaginary line” that connects it to the sun sweeps equal amount of area in equal time intervals • Closer to sun = faster • Farther away = slower
Kepler’s 3rd Law • The square of a planet’s orbital period is proportional to the cube of its distance from the sun • Orbital period - how long it takes to orbit the sun • Astronomical Unit (AU) – average distance between Earth and sun – 150 million km • T2 = d3 ; T = orbital period, d=distance from sun in AUs
Kepler’s 3rd Law • T2 = d3 • Mars has period (T) of 1.88 years (T = 1.88) • (1.88)2 = 3.54 • d3 = 3.54 • d = 1.52 AU
Kepler’s Laws Tri-fold • Use a tri-fold/brochure to explain Kepler’s 3 Laws. There should be no words other than labeling each 3rd as to which law you are demonstrating. You may also use the formula for Kepler’s 3rd law.
Orbits • Barycenter – point between two objects where they balance each other • When a moon orbits planet, or planet orbits a star, both bodies are orbiting around a point that lies outside of the larger body (star/planet) http://www.youtube.com/watch?v=rKo6tfFtZg8 (2:59) http://www.youtube.com/watch?v=KnHUAc20WEU http://en.wikipedia.org/wiki/Barycentric_coordinates_(astronomy)
Orbits • The Sun is NOT a stationary object. • Sun moves as the planets tug on it • Sun orbits the solar system’s barycenter
Moon and Earth Relationship • Earth pulls on the moon, and moon pulls on Earth • This “tugging” from the moon can cause the Earth to bulge
Moon and Earth Relationship • Earth’s solids cannot give, however water does, causing our tides • Two high tides and two low tides a day • 12hrs and 25 min between two high tides
Moon and Earth Relationship • Rise and fall daily due to Earth, Sun, and Moon interactions • Since earth is rotating, we experience two tides each day
Moon and Earth Relationship • Spring Tides – when moon and sun interact together and form extreme tides. • Occurs during full and new moons
Moon and Earth Relationship • Neap Tides – moon and sun pull at right angles and cancel each other out...very weak tides http://www.youtube.com/watch?v=l37ofe9haMU http://www.youtube.com/watch?v=rRPtNAA-9UE