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发帖数: 1994 | 1 Mercury on the Horizon
Credit & Copyright: Juan Carlos Casado
Explanation: Have you ever seen the planet Mercury? Because Mercury orbits so close to the
Sun, it never wanders far from the Sun in Earth's sky. If trailing the Sun, Mercury will be
visible low on the horizon for only a short while after sunset. If leading the Sun, Mercury will
be visible only shortly before sunrise. So at certain times of the year an informed skygazer
with a little determination can usually pick Me |
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