This summit is 7830 meters high, and it is quite easy to approach – no gorges, no cliffs, no glaciers. Nevertheless, only two Americans, John Young and Charles Duke, managed to climb it. Yet, it should be added that before they ascended, they had to fly to the Moon in Apollo 16, because the summit in question is the highest point of the Moon. How did they measure the altitude – isn’t there no thing as a sea level on the Moon? The Guinness Book of Records explains: lunar altitudes are measured relative to the surface of a sphere with a radius equal to the equatorial radius of the Moon, i.e., 1738 kilometers.