Where does moon water come from?
Hydrogen is the most common element of our Universe. Oxygen is a heavier element but still very common now that Population 1 stars such as ours exist. The bonding of hydrogen and oxygen is quite simple. The existence of the molecule water is therefore quite common throughout our Solar System and other star systems. Most of this molecule is not in liquid form as it is on Earth. Water in one form or another is found on every planet in our Solar System. Most of the water came from comet impacts when our Solar System was forming but water ice also existed prior to the formation of planets and is what caused the gas giant planets to become so large. Comet collisions also occured after the Moon was formed out of the Giant Impact. Gravity has much to do with whether the orb retains the water or if it escapes into the atmosphere or space. Our Moon is relatively large. It contains water because of the oxygen isotopes within it when it formed, and from comet collisions. The lack of liquid water
