If a planet had a semi-major axis length of 2.3 AU as it orbits the Sun, what would be its period in years?

a. 1.74 years
b. 2.3 years
c. 3.49 years
d. 12.2 years

1 answer

Using Kepler's third law, the period of an orbiting planet can be calculated using the formula:

period^2 = semi-major axis^3

Plugging in the values given:

period^2 = (2.3 AU)^3

Simplifying:

period^2 = 12.167 AU^3

Taking the square root:

period = √12.167 AU^3

Calculating the square root:

period ≈ 3.49 years

The correct answer is c. 3.49 years.