Kepler's Laws of Planetary Motion PDF

Kepler’s Laws of Planetary Motion  1st Law: As planets orbit the Sun, they do so in elliptical orbits. An ellipse is a flattened circle/oval.  Eccentricity is a measure of how round or oval an orbital path is  Eccentricity = distance between foci len...

Kepler’s Laws of Planetary Motion  1st Law: As planets orbit the Sun, they do so in elliptical orbits. An ellipse is a flattened circle/oval.  Eccentricity is a measure of how round or oval an orbital path is  Eccentricity = distance between foci length of the major axis A perfect sphere has one central point. Ellipses have 2 focal spots called foci.  The closer the eccentricity is to 1.000, the more eccentric (elliptical/oval) the orbital path is. ***1.000 represents maximum eccentricity (a straight line) *** 0.000 represents a perfect circle (minimum eccentricity)  Earth’s orbit is a slightly eccentric ellipse with the Sun at a focus. 2.) Kepler’s Second Law of Planetary Motion  If an imaginary line connects the Earth to the Sun, it will sweep through equal areas in equal time  This means that the planet travels faster while close to the sun and slows down when it is farther from the sun.  Earth orbits the Sun from west to east = counterclockwise  Earth orbits the Sun ~1*/day.   Because E’s orbit is slightly elliptical, our distance from the Sun changes throughout the year.  We are closest to the Sun on January 3rd (Perihelion) and farthest  from the Sun on July 4th (Aphelion).  3.) Kepler’s Third Law  Planets closer to the Sun have a shorter period of revolution than those farther from the Sun. This is due to the fact that if a planet is closer, it has a shorter distance to travel  He was able to mathematically prove this.