As Venus was closer to the Earth, its parallax angle would be larger, and Halley worked out that by using Venus it would be possible to measure the Suns distance to 1 part in 500.
The parallax principle can be extended to measure the distances to the stars.
视差原理可以扩展到测量地球到恒星的距离。
3
The most precise way to measure an object's distance is to use "parallax" - differences in perspective created by viewing an object from different angles.