How does sun and the moon cause tides on the earth?
The effect of gravity depends on the distance to the object with mass causing the pull. Consequently the side of the earth near to the moon feels a stronger pull than the middle, which in turn feels a stronger pull than the far side. The oceans can flow to react to this pull, so there is a bulge of water pointing towards the moon, and one pointing away (because the solid earth is pulled towards the moon more than the water on the far side). Meanwhile the earth rotates, while the moon only orbits much more slowly, so different bits of the earth point towards the moon and different times of day, so we get a high tide when we point towards the moon, and a low tide size hours later, then another hightide when we point away from the moon (another size hours later) etc. There are two high tides per day. As for the sun – it also has a similar effect to the moon, but the greater distance makes the effect weaker. When the sun and moon are in line (i.e. full moon and new moon) the tidal forces d
