Theory of tides

Imagine you live by the ocean, and you love going to the beach. The beach is a place where the water meets the sand, and you can play with your toys, build sandcastles, and go for a swim. But have you ever noticed that sometimes the water is higher up on the beach than other times? This is because of something called tides.

Tides are like giant waves in the ocean that happen twice a day. They happen because of the moon and the sun. The moon is very big, and even though it's far away, its gravity can pull the water towards it. The side of Earth that is facing the moon will feel this tug more strongly, and so the water on that side will bulge outwards towards the moon.

Now, the Earth is spinning really fast, so as it turns, the part of the water that's bulging out will move with it. As this water moves, it causes high tides in some places and low tides in others. When the water is bulging out, it's high tide, and when it's not, it's low tide.

But the sun also has its own gravity, which affects the tides too. When the sun and moon are lined up with the Earth, their gravity combines, and the water bulges out even more. This is called a spring tide, and it happens twice a month when the moon is full or new.

So that's why the tides happen - it's all because of the moon and the sun pulling on the water in the ocean. And now you know why sometimes the water is high up on the beach and sometimes it's far away!