Kepler’s Laws

Kepler’s LawsJohannes 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 LawThe path of each planet around the sun is an ellipse with the sun at one focus

Kepler’s 2nd LawEach 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 LawThe 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 LawT2 = 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.

OrbitsBarycenter – 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://en.wikipedia.org/wiki/Barycentric_coordinates_(astronomy)

http://www.youtube.com/watch?v=KnHUAc20WEU

http://www.youtube.com/watch?v=rKo6tfFtZg8(2:59)

OrbitsThe 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