The Universe Made Simple/The Solar System/Navigation
The Earth itself is very interesting, however, so is its moon. The Moon or Luna is 384,000 kilometers from the Earth. It has a radius of 1,738 kilometer and weighs 7.35 x 10^22 kilograms. The moon is 1/80th the mass of the earth and 1/4th its diameter. An interesting thing about the moon is that it slows the Earth’s rotation by two milliseconds every century. This means that 900 million years ago, there were 481 days and 18 hours in an Earth year. The moon’s orbit is very nearly circular and one lunar day and night is almost fifteen Earth days. The temperature on the moon changes drastically depending on whether it is day or night. At night, the temperature can drop to almost -113° Celsius. During the day, temperatures can reach 100° Celsius. This is all because the moon does not have surface water or an atmosphere.