How do you calculate the distance between stars and the earth?
For near by stars a method called parallax is used.
For far away stars Cepheid variables are used as standard candles and distance calculated .
picture credit windows 2u.
Earth travels 300 million kilometers in one year and this is taken as base.
Angle is known the distance can be calculated by trigonometry
The cephid variables have a PROPERTY ITS PERIOD OF PULSATION AND LUMINOSITY HAVE RELATION tTHIS IS USED AS STANDARD CANDLE AND WE CAN CA;CALCULATE THE DISTANCE BY LAW OF RADIATION..