Question

Kepler’s 1st Law states that ________________________.

A. planets move in a circular path
B. planets move in elliptical paths
C. planets move at a constant speed
D. a planet’s orbital radius is related to its period

Answer 1

Kepler's 1st law of planetary motion says that planets move in
orbits that are ellipses, with the sun at one focus of the ellipse.

(Choice D. is the idea behind Kepler's 3rd law.
Choices A. and C. have no basis in fact at all.)

Answer 2

Kepler's 1st Law states that planets move in elliptical path. The correct option among all the options given in the question is option "B".Kepler was the person that set out to determine the path of planets with the sun at the center. By the method of trial and error, he discovered the fact that the sun lied at the focus and the planets revolved around it in a elliptical path. This discovery changed the way people thought about the movement of planets and sun.