Question

kepler discovered that by using a planets orbital period, it is possible to determine its ______ from the sun.

a time

b length

c distance

d mass

Explanation:

Kepler's Third Law (the Law of Periods) relates a planet's orbital period to its average distance from the Sun. The law is \( T^2 \propto a^3 \), where \( T \) is the orbital period and \( a \) is the semi - major axis (a measure of the planet's distance from the Sun). So, using the orbital period, we can determine the planet's distance from the Sun. Option a (Time) is incorrect as we are using the orbital period (a time - related quantity) to find another quantity, not time itself. Option b (Length) is too vague, and option d (Mass) is not related to the orbital period in this way (orbital period of a planet around the Sun doesn't directly give its mass).

Answer:

c. Distance