A transiting extrasolar planet is observed to block 1% of its host star's light. How does the size of this planet compare to the host star?
A)The planet's radius is 10% of the host star's radius.
B)The planet's radius is 1% of the host star's radius.
C)The planet's radius is 0.1% of the host star's radius.
D)The planet is the same size as the host star.

Question

Quizplus · Accepted Answer

The amount of light blocked during a transit (1% in this case) is proportional to the square of the ratio of the radii of the planet to the star. Therefore, if the planet blocks 1% of the star's light, its radius is the square root of 0.01, or 10% of the star's radius.

A Transiting Extrasolar Planet Is Observed to Block 1% of Its