Next they had to decide on a "natural" length. They chose one ten-millionth of the distance from the Equator to the North Pole.

接下来他们必须决定一种“自然的”长度，他们选择了从赤道到北极距离的一千万分之一，他们将它称作一米。

youdao

The Earth isn't completely spherical - land at the North Pole is a number of kilometres nearer to the core of the planet than land at the Equator.

事实上，气球并非是一个完美的球体，北极地区要比赤道地区更加接近地心，两地之间的这一差距大概是在数公里。

youdao

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。

youdao