Why does the Doppler method only provide a measure of the minimum mass of a planet?Only a small part of the planet's motion is measured.Without a transit observation, the size and therefore density of the planet is unknown.We do not know the exact composition of the planet.The Doppler shift tells only part of a host star's orbital speed $($the part toward and away from the observer$).$We do not have the technology to make a direct image of a planet yet.