Editing Stellar parallax (section)

=== Variants ===

Stellar parallax is most often measured using '''annual parallax''', defined as the difference in position of a star as seen from Earth and Sun, i.e. the angle subtended at a star by the mean radius of Earth's orbit around the Sun. The [[parsec]] (3.26 [[light-year]]s) is defined as the distance for which the annual parallax is 1&nbsp;[[arcsecond]]. Annual parallax is normally measured by observing the position of a star at different times of the year as Earth moves through its orbit.

The angles involved in these calculations are very small and thus difficult to measure. The nearest star to the Sun (and also the star with the largest parallax), [[Proxima Centauri]], has a parallax of 0.7685&nbsp;±&nbsp;0.0002&nbsp;arcsec.<ref name="Gaia" /> This angle is approximately that [[subtended]] by an object 2 centimeters in diameter located 5.3 kilometers away.