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发帖数: 1994 | 1 Outbound from Mercury
Explanation: After just passing Mercury, the robot spacecraft Mariner 10 looked back. The
above picture is what it saw. Mercury, the closest planet to the Sun, is heavily cratered much
like Earth's Moon. As Mercury slowly rotates, its surface temperature varies from an
unbearably cold -180 degrees Celsius in the half facing away from the Sun, to an unbearably
hot 400 degrees Celsius in the half facing toward the Sun. Mercury is slightly larger than
Earth's Moon and much den |
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