polar cap

基本解释

Earth will become a desert planet, with at most a shrunken polar cap and only traces of precious liquid.
而若再过一个十亿年，地球的海洋就会被蒸干，那时候的地球就会变成一片荒漠，最多只在极地附近还有一些冰山，液体物质将变成痕量物质，十分宝贵。
As often seen through an astronomical telescope eyepiece, the planet's orientation is inverted, with Mars' north polar cap at the bottom.
由于往往是通过天文望远镜的目镜拍摄，火星的方向是颠倒的，行星的北极冠在下面。
The pinkish deposits constitute a vast south polar cap believed to contain methane ice, which would have reacted under sunlight to form pink or red compounds.
这些固态氮冰在阳光照射下会产生化学反应，生成粉色或红色的化合物。