Temperature and seasons

Because of its closeness to the Sun, surface temperature variations are extreme on Mercury, more than on any other planet. You could roast during the day at 430°C, and freeze during night at -180°C. The high day temperature would be hot enough to melt the metals zinc and tin. One day on Mercury is equal to 58.65 Earth days, so it takes a long time to warm up from the cool of night and it takes a long time to cool down from the heat of day.

Mercury is not the hottest planet on average. The temperature on Venus is slightly higher than on Mercury but is more stable because of the thick clouds on that planet.

On Earth, the seasons change in a regular way because the rotational axis is inclined (at 23.5° from the perpendicular to its orbital plane). As a result, each hemisphere on Earth receives more direct sunlight during one part of the orbit than the other. Mercury's axis is very nearly perpendicular to its orbital plane (2° from perpendicular), so no seasonal changes occur. Some craters near Mercury's poles never receive any sunlight and are permanently cold.

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