What causes tidal bulging?

Tides happen because the moon pulls on Earth’s water, making it bulge out on two sides.

Imagine you're playing with a balloon that's filled with water. If you pull one side of the balloon with your hand, it stretches and bulges out on both the side you’re pulling and the opposite side. That’s kind of what happens with Earth and the moon, the moon pulls Earth’s ocean, making two bulges: one facing the moon and one on the far side.

When the moon tugs on the ocean, it stretches it like a rubber band. The part of the ocean closest to the moon gets pulled toward the moon, creating a bulge, this is where high tide happens. On the other side of Earth, the water also bulges because the pull makes everything else move away from that spot, kind of like when you pull on one end of a rope and the other end moves too.

As Earth spins, different parts of the ocean get hit by these bulges, causing high tide where the bulge is and low tide where it’s not. It's like having two giant water hills rolling around the planet as you go about your day!