How is the distance between stars and the earth calculated?
Stellar parallax is the apparent angular displacement of a star when observed from two sufficiently-spaced known locations
A convenient choice is the same observatory, with time spacing that is (sufficiently large integer) N days.
If N is the exact number of 24-hour days and
For conversion to light years (ly), use 1 AU =
Sample Data: N = 7,
The approximation to the distance of the star
= 8.259 E+06 AU
= 131.3 light years.
(It is assumed that the precision in the Radio Telescope for parallax is as good as 0.001".)