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Friday: November 8, 2013. Science In The News. Daily Science Question pg 17. Describe the shape of a planetary orbit? What does it look like? Where is the Asteroid Belt located? By what planet?.
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Friday: November 8, 2013 Science In The News
Daily Science Question pg 17 • Describe the shape of a planetary orbit? What does it look like? • Where is the Asteroid Belt located? By what planet?
Learning Target (LT) # 6Kepler’s Laws of Planetary Motion 11/08/13_____________________________Cornell StyleWrite only underlined text from slides 33
Johannes Kepler • Found patterns in planet movement; developed 3 laws of planetary motion.
1. Law of Ellipses 2. Law of Equal Areas 3. Law of Periods
Eccentricity- • The degree of elongation of an elliptical orbit.
1. Law of Ellipses: all orbits are elliptical, from nearly circular to parabolic. e = 0 e = 1 “e” is the eccentricity (how stretched to a max of “1”)
Kepler’s second law states that equal areas are covered in equal amounts of time as an object orbits the sun. • Both shaded triangles have the same area (think carpet). 2. Law of Equal Areas:
Describes the speed of objects at different points. • Objects move faster closer to perihelion and slower at aphelion.
Orbital Period • The time required for a body to complete a single orbit.
Daily Science Question pg 17 • Kepler’s first law states that each planet orbits the sun, not in a circle, but in an ellipse. TRUE or FALSE • Kepler’s law that describes how fast planets travel at different points in their orbits is called the law of ____________.
Learning Target (LT) # 6Kepler and Newton 11/12/13_____________________________Cornell StyleWrite only underlined text from slides 35
Law of Periods: • Relates the planets average distance from Sol to the time it takes the planet to complete 1 complete orbit. • Measured in Earth years in distance of AU’s. K x a3 = p2(K =1)
p = orbital period a = distance from Sol a3 = p2 Orbital periods measured = distance from the Sun.
Example: Jupiter’s orbital period is 11.9 Earth years a3= p2 p=11.9 p2=142 p2=a3 a3=142 a=5.2 Jupiter’s average distance from Sol is 5.2 AU’s.
Newton noticed that they also worked for all other objects. WHY? • Inertia – tendency of object to resist change in motion unless outside force acts on it.
But what force is causing the curve of the elliptical orbits, of a thrown ball, of a launched arrow…the apple falling from a tree? • Objects in motion will stay in motion, unless… Newton’s answer: Gravity!
Gravity is effected by distance and mass. The closer the planet is to the sun, the stronger the gravity AND the faster the planet moves in its orbit,
In Review: • Kepler’s 1st law states planets orbit the sun in curved paths called ellipses • Kepler’s 2nd law states planets closer to the sun travel faster than those further away. • Kepler’s 3rd law relates a planet’s average distance from around the sun to the time it takes to make one orbit.