For example, Polaris won't always be the pole star!

比如，北极星不会永远处于北极。

For ancient Egyptians, the star Thuban was the pole star, and in about 11,000 years that position will be held by the bright star Vega.

对古埃及人来说，紫微右垣曾经是他们的北极星，大约11000年后，这一位置将会被另一个亮星织女星占据。

But Polaris has not always been the pole star, precisely because of this wobble on the axis of the Earth.

但北极星并不总是极星，这恰恰是由于地球轴线的摆动造成的。

When weather conditions were not good or where land was no longer visible, Roman mariners estimated directions from the pole star or, with less accuracy, from the Sun at noon.

当天气状况不佳或不再可见陆地时，罗马水手会根据极星或中午太阳估计方向，但准确性较低。