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The moon was formed when the early Earth was impacted by a Mars-sized body; It ejected billions of tons of material, and knocked our rotation to a 23.5 degree angle with respect to our orbit.

Over time, the material that was ejected by the impact began to collect, forming the moon. It was much closer to Earth immediately after it formed, and our day was very much shorter. Over time, the tidal force of the moon slowed our day, and as we slowed, the energy of our rotation was 'stolen' by the moon, boosting it's orbit. (It is still moving away, at about 1 1/3 inches per year.)

So, the moon where it is now - and, at about 1/80th the mass of Earth, and the sun - 93 million miles away - create about the same amount of tidal force on the Earth's oceans.