Answer:
1. A model in the universe in which the sun, moon, stars, and planets all revolve around Earth.
2. Why did stars and planets get brighter at different times of the year if they were all moving in perfect circles around the earth? Why do some planets seem to stop and reverse direction in the sky?
3. Not all astronomical bodies revolve around Earth. Only the moon orbits earth, but that's all. In fact, Earth revolves around the sun just like all the other planets.
4. The parts about the planets revolving around something and the fact that they revolve.
5. Mass and distance.
6. The law of universal gravitation states that every mass attracts other masses with a force that is directly proportional to the product of the two masses and is inversely proportional to the square of the distance separating them.
7.
1. All objects with mass (no matter how small) exert a gravitational attraction.
2. The more massive an object is, the stronger its gravitational force.
3. The greater the distance between the objects, the weaker the gravitational force.
Step-by-step explanation: