What causes ocean tides to rise and fall twice a day?

The ocean tides go up and down because the Moon pulls on Earth’s water, just like when you pull a toy boat in a bathtub.

Imagine you're playing with your favorite bucket of water. When you gently pull the bucket toward you, the water inside moves too, it goes up on the side closest to you and down on the opposite side. That's what happens with the ocean when the Moon pulls Earth.

The Moon is like a big magnet, but instead of pulling metal, it pulls water. When the Moon is close to Earth, it pulls ocean water toward itself, making the tide rise on that side of Earth. At the same time, the tide falls on the opposite side because the Earth is pulled slightly away from the water there.

Since the Moon goes around Earth once every day, it gives two pulls, one in the morning and one at night. That’s why we usually get two tides each day: one when the Moon is above us, and one when it's on the other side of Earth.

So, just like your bucket moves with your pull, our oceans move with the Moon’s gentle tug, and that’s how tides happen!