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.
This means that near the north or South Pole you are actually closer to the centre of the earth-where the Angle is being measured from-than you would be at the equator.
这就意味着，如果你身处南极或北极附近，你离地心的距离就比在赤道更近一些——纬度的测量就与地心有关。
3
When you get closer, you see that each horizontal section is made up of two pieces that converge in a right angle.