Derived from parallax
-
apparent angular shift of a nearby star
relative to
more distant stars as observer’s point of
view changes
= Earth orbits Sun (need very large separation of
views)
Parallactic
angle = parallax = ˝ x apparent shift
(1 parsec = distance at which parallax =
1 arcsec)
• proper motion -- nearby stars appear to move
faster
Measuring
stellar distances