Using Parallax to Determine Distance

Using Parallax to Determine Distance
(c) As Earth orbits the Sun, a nearby star appears to shift its position against the background of distant stars. The star’s parallax angle (p)
is equal to the angle between the Sun and Earth, as seen from the star. The stars on the scale of this drawing are shown much closer
than they are in reality. If drawn to the correct scale, the closest star, other than the Sun, would be about 5 km (3.2 mi) away.
(d) The closer the star is to us, the greater the parallax angle p. The distance to the star (in parsecs) is found by taking the inverse of the parallax
angle p (in arcseconds), d = 1/p.