The electron density is much lower at night in the polar cap areas.

夜间进入极盖区后，电子密度则很低。

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This year, Shanshan's dad was a pilot on flights over the Polar Cap.

今年，姗姗的爸爸成为了飞两极冰帽的航班上的飞行员。

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Zuber and her colleagues also analyzed Mars's much larger northern polar cap.

尤伯和她的同事也分析了火星上要大得多的北部极地冰冠。

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They were photographed in September 1998 in Chasma Boreale, a giant trough at Mars' north polar cap.

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PASADENA, California (CNN) -- The summer has warmed up the south of Mars, melting away much of its icy polar cap.

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Before the research papers of the IPY's scientists are published, for those living on the southern polar cap, climate change is already palpable.

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