posted by Liz on .
Which statement about stellar motion is incorrect?
A.In general, the closer a star is, the more its proper motion.
B.The radical velocity is measured by the Doppler shift.
C.The transverse velocity is measured by the proper motion and distance. D.Like parallax, proper motion is measured over intervals of exactly six months.
E.The Pythagorean Theorem relates space, transverse, and radial velocities
D. is incorrect. Proper motion is the long term trend in stellar position change, with the parallax taken out. It may take many years to measure it, and the measurements should be taken at the same time of year, to eliminate the parallax effect