4. Which did Kepler notice about planetary motion that caused him to propose his FIRST law of orbital motion?
*
1 point
The planets have circular orbits.
The distance between Mars and the sun is constant.
The distance from a planet to the sun varies as it orbits
Most planets have highly elliptical orbits.
The distance from a planet to the sun varies as it orbits.
Kepler noticed that the distance from a planet to the sun varies as it orbits, which led him to propose his FIRST law of orbital motion.
To answer this question and understand why Kepler proposed his first law of orbital motion, let's review the options provided:
1. The planets have circular orbits.
2. The distance between Mars and the sun is constant.
3. The distance from a planet to the sun varies as it orbits.
4. Most planets have highly elliptical orbits.
Kepler's first law, also known as the law of ellipses, states that the planets move around the sun in elliptical paths, with the sun at one of the foci of the ellipse. Therefore, option 4, "Most planets have highly elliptical orbits," is the correct answer.
To arrive at this conclusion, Kepler made careful observations of the planets' positions over time. He noticed that the planets' distance from the sun changed during their motion. By studying the planetary orbits, he realized that the shape of these orbits could not be a perfect circle. Instead, they had an elliptical shape, with the sun located at one of the foci.
Therefore, Kepler's observation of the planets' elliptical orbits led him to propose his first law of orbital motion.