How to use trigonometric parallax method to calculate planetary distance? Where does this distance go from?

How to use trigonometric parallax method to calculate planetary distance? Where does this distance go from?

It's not easy to measure the distance between celestial bodies by trigonometric parallax method. Astronomers divide the celestial bodies to be measured into several grades according to the distance. The nearest celestial bodies are not more than 100 light years away from us (1 light year = 9.46 &  1012km). Astronomers measure it by trigonometric parallax method