DRILL SIX What causes the change of constellations

Objective: Explore Kepler’s three laws of planetary motion using an interactive computer simulation AGENDA:

3 THE EARLY YEARS Geocentric solar system. Earth-centered solar system where the planets and

But the geocentric view doesn’t explain retrograde motion. Retrograde- the apparent backwards motion of

5 The Birth of Modern Astronomy In the early 1500 s, Copernicus suggested that

Copernican Solar System The heliocentric view explained why Mars is in Retrograde occurs because

Kepler’s Three Laws In the early 1600 s, Johannes Kepler proposed Three Laws of

Kepler’s First Law: (The Law of Ellipses) The path of the planets around the

Kepler’s Second Law: A line joining a planet and the sun sweeps out equal

Kepler’s Third Law The period of a planet's orbit (how long it takes the

Gravity, Orbits and Kepler’s Laws Go to phet. colorado. edu Click on “play with

Journal Write 1. As an astronaut travels from Earth to the Moon, describe how

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DRILL: SIX What causes the change of constellations with the seasons? It is caused by the Earth’s orbit around the Sun

Objective: Explore Kepler’s three laws of planetary motion using an interactive computer simulation AGENDA: Kepler’s 3 Laws Notes Gravity and Orbits Phet Quiz next class!

3 THE EARLY YEARS Geocentric solar system. Earth-centered solar system where the planets and the Sun revolve around the Earth. • Invented by the Greeks and believed for 1600 years •

But the geocentric view doesn’t explain retrograde motion. Retrograde- the apparent backwards motion of planets in the sky

5 The Birth of Modern Astronomy In the early 1500 s, Copernicus suggested that the Earth rotates on an axis and revolves around the Sun. Heliocentric solar system- the sun at the center He used circles for the orbits of planets (even though he knew theory didn’t match predicted patterns)

Copernican Solar System The heliocentric view explained why Mars is in Retrograde occurs because the planets further from the sun are moving slower in their orbits than the planets closest to the sun 6

Kepler’s Three Laws In the early 1600 s, Johannes Kepler proposed Three Laws of Planetary Motion. These laws describe the motion of planets around the Sun.

Kepler’s First Law: (The Law of Ellipses) The path of the planets around the sun is elliptical in shape, with the center of the sun being located at one focus.

Kepler’s Second Law: A line joining a planet and the sun sweeps out equal areas during equal intervals of time Planets travel faster the closer they are to the Sun

Kepler’s Third Law The period of a planet's orbit (how long it takes the planet to go around the Sun), determines that planet's distance from the Sun. ***It also tells us that planets that are far away from the Sun have longer periods than those close to the Sun. They move more slowly around the Sun.

Gravity, Orbits and Kepler’s Laws Go to phet. colorado. edu Click on “play with sims” Click on “physics” Open the “Gravity and Orbits” simulation Using the “Model” tab follow ALL directions carefully Everyone needs to complete their own packet

Journal Write 1. As an astronaut travels from Earth to the Moon, describe how the force of gravity changes and the factors that influence the force of gravity. 2. Explain this statement: Even though the sun is much larger than the moon, the moon has a greater gravitational effect on the Earth. Support your answer with evidence from Newton’s Universal Law of Gravitation.