在火星的两极，冰川，从数以千计的阶层组成，是过去气候变化的证据。
At Mars' poles, glaciers, formed from thousands of fine strata, are evidence of past climatic fluctuations.
“这些埋藏着的冰原从两极一直延伸到(北纬和南纬)45度左右，没能完全覆盖半个火星，但(覆盖面)接近这一水平。”Shane Byrne表示。
"These buried ice sheets that extend from the poles all the way down to 45 degrees or so (north and south latitude) don't quite cover half of the planet, but (they) come close," he said.
像其它行星一样，火星不是十分圆的，由于自转，两极稍偏。
Like other planets, Mars is not perfectly round; it is flattened at the poles because of its spin.
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