The origin of the Moon is still a mystery. Some scientists believe that the Moon was formed before the Earth. The Earth emerged about 1,000 years after the Moon. - The Moon is shrinking. It has shrunk by around 200 meters across its diameter in the last billion years. The Moon is slowly moving away from the Earth at a rate of 3.8 cm (1.5 inches) per year. Scientists believe that the Moon was about 24,000 Km (15,000 miles) from Earth, now it is 384,400 km (238,855 miles). The Moon's days and nights are longer than the Earth's. One ""Moon Day"" is about 14 Earth days, same for the ""Moon Nights."" - The Moon is home to some massive mountains. The highest mountain is about 5,500 meters (18,045 feet) high, more than half the height of Mount Everest. - The Moon is an excellent source of building materials, water, fuel, oxygen, and other useful resources that are significant for modern electronics and batteries. The Moon has over 1 million tons of Helium-3, a non-polluting nuclear fuel. At the current rate of energy consumption, this will take care of 10,000 years of worldwide demand.