An astronomer is trying to detect an exoplanet via the radial velocity method. Which of these changes to a particular planet will make it harder to detect, if everything else about the planet is unchanged?
A) decreasing its orbital period
B) decreasing its mass
C) decreasing its radius
D) decreasing its albedo

Question

Quizplus · Accepted Answer

Decreasing the mass of an exoplanet makes it harder to detect using the radial velocity method because the gravitational influence of the planet on its host star is reduced, leading to smaller shifts in the star's velocity that are harder to detect. The radial velocity method relies on detecting variations in the velocity of a star due to the gravitational pull of an orbiting planet, so a less massive planet exerts a weaker force and produces smaller velocity changes.

An Astronomer Is Trying to Detect an Exoplanet Via the Radial