The Inner Planets: The Moving Planets

The video explores the evolution of astronomical theories, starting with the belief that the Sun revolved around the Earth. Copernicus introduced the heliocentric model, suggesting that planets orbit the Sun. Kepler later refined this model, proposing that planets move in elliptical orbits. The concept of an ellipse is explained, likening it to an oval shape. Newton's laws of motion and the force of gravity are discussed, explaining why planets maintain their orbits around the Sun.

Who proposed the idea that the Earth and other planets orbit the Sun?

• Galileo Galilei

• Isaac Newton

• Nicolaus Copernicus

• Johannes Kepler

What shape did Johannes Kepler propose for the orbits of planets?

• Circle

• Square

• Triangle

• Ellipse

What is an ellipse?

• A square

• A straight line

• A perfect circle

• An oval shape

According to Isaac Newton, what keeps planets in motion around the Sun?

• Electricity

• Wind

• Inertia

• Magnetism

What force prevents planets from flying off into space?

• Friction

• Magnetism

• Gravity

• Electricity