Kepler determined that planets change their speed as they travel around the sun. This happens due to all of the following EXCEPT
A). The sun's gravity makes the planets slow as they get closer
B). The sun's gravity pulls against the planet's inertia in some places
C). The sun's gravity pulls with the planet's inertia in some places
D). The planets' orbits are elliptical
A). The sun's gravity makes the planets slow as they get closer
The correct answer is C). The sun's gravity pulls with the planet's inertia in some places.
To determine the correct answer, let's examine each option one by one:
A) The sun's gravity makes the planets slow as they get closer:
This is one of the key insights of Kepler's laws. According to Kepler's second law, known as the law of equal areas, planets move faster when they are closer to the sun and slower when they are farther away. So, this option is not the correct answer.
B) The sun's gravity pulls against the planet's inertia in some places:
This statement is correct. Kepler's first law, known as the law of elliptical orbits, states that planets move in elliptical paths around the sun. In some parts of their orbits, the gravitational force of the sun is acting in the opposite direction to the planet's inertia, causing the planet to slow down.
C) The sun's gravity pulls with the planet's inertia in some places:
This statement is also correct. In some parts of their orbits, the gravitational force of the sun and the planet's inertia act in the same direction, causing the planet to speed up.
D) The planets' orbits are elliptical:
This statement is true. Kepler's first law states that the paths of planets around the sun are elliptical in shape.
Therefore, the correct answer is A) The sun's gravity makes the planets slow as they get closer.