What if Mercury is our moon

A special feature of Mercury is that it rotates exactly three times around its own axis during two orbits around the sun. In colloquial language, a “day” means the time span between two comparable positions of the sun, for example from sunrise to the next sunrise. On earth this period of time is almost identical to the rotation of the earth around its own axis. This does not apply to Mercury:

Suppose you woke up as a resident of Mercury in the morning at a beautiful sunrise and waited 59 earth days for the planet to rotate once on its own axis. Then you would have already covered two thirds of the way around the sun, but it would still be day. During the second rotation around your own axis it would be night for you, and only after completing the third rotation around your own axis would you experience the next sunrise.

For an observer on Mercury, it would take two Mercury years from one to the next sunrise. In addition, an earth year is about four times longer than a Mercury year. A 40-year-old inhabitant of the earth would have celebrated 160 birthdays on Mercury, but only experienced 80 sunrises!

Of all the planets in our solar system, there are the greatest temperature differences on Mercury. Since it has almost no atmosphere that could hold the temperature on the planet, the surface temperature fluctuates from -170 ° C on the night side and 430 ° C on the day side by at least 600 ° C!