Noun
proper motion (plural proper motions)
(astronomy) The change in apparent position of a celestial body due to that body's velocity relative to the Sun.
61 Cygni first attracted the attention of astronomers when its large proper motion was first demonstrated by Giuseppe Piazzi in 1804. Source: Internet
A high proper motion is an indicator of closeness to the Sun. citation Nearby stars can traverse an angle of arc across the sky more rapidly than the distant background stars and are good candidates for parallax studies. Source: Internet
A proper motion of 1 arcsec per year at a distance of 1 light-year corresponds to a relative transverse speed of 1.45 km/s. Source: Internet
As the stars of Alpha Centauri approach the Solar System, the measured proper motion and trigonometric parallax slowly increase. Source: Internet
A negative value for proper motion in RA indicates the sky motion is east to west, in declination north to south. Source: Internet
Animation of proper motion in 400,000 years (cross-eyed viewing ). Source: Internet