Question

in addition to proposing that planetary orbits are elliptical, what other modification did kepler make to copernicuss model? planets closer to the sun move faster. planets spin in an epicycle while orbiting earth. venus has phases due to its orbiting of the sun. earths rotation causes the rising and setting of the sun.

Explanation:

Kepler's second - law (law of equal areas) states that a line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time. This implies that planets closer to the Sun move faster. Copernicus' model had circular orbits and did not account for this speed - variation. The other options are either not related to Kepler's modifications (planets spin in an epicycle while orbiting Earth is a Ptolemaic concept, Venus has phases was known from Galileo's observations related to heliocentrism but not a Kepler - specific modification, Earth's rotation causing Sun's rising and setting is a basic heliocentric concept not a Kepler modification).

Answer:

Planets closer to the Sun move faster.