How is stellar parallax calculated?

Stellar parallax is calculated using the formula ( d = \frac{1}{p} ) where ( d ) is the distance to the star in parsecs and ( p ) is the parallax angle measured in arcseconds. This relationship arises because the apparent shift in a star's position (its parallax) is inversely proportional to its distance from Earth. When a nearby star is observed from two different positions in Earth's orbit, it appears to move against the background of more distant stars, and this angular measurement forms the basis of the parallax effect.

This formula allows astronomers to determine how far away a star is based on how much it seems to move due to the Earth's orbit around the Sun. Thus, if you measure the parallax angle (in arcseconds), you can easily compute the distance to the star in parsecs using this accurate formula. The units conform correctly, making calculations straightforward and intuitive for determining distances in the cosmos.