Question

How can we calculate one parsec?​

Answer 1

Calculating the value of a parsec. In the diagram above (not to scale), S represents the Sun, and E the Earth at one point in its orbit. Thus the distance ES is one astronomical unit (au). The angle SDE is one arcsecond (13600 of a degree) so by definition D is a point in space at a distance of one parsec from the Sun.