Question

What is the accuracy of the parallax method?

Answer 1

Astronomers can measure a star's position once, and then again 6 months later and calculate the apparent change in position. The star's apparent motion is called stellar parallax. The distance d is measured in parsecs and the parallax angle p is measured in arcseconds.

Answer 2

Space based telescopes can get accuracy to 0.001, which has increased the number of stars whose distance could be measured with this method.