S2E1040 - The Ground Beneath You Rises and Falls Twice a Day

The ground beneath your feet may feel completely still.

But it isn't.

Twice a day, the solid Earth itself rises and falls by measurable amounts.

The reason is surprisingly familiar:

The Moon.

Just as the Moon's gravity helps create ocean tides, it also produces tides in the solid Earth.

The effect is called an Earth tide, or solid Earth tide.

As the Moon and Sun pull on our planet, the Earth's crust flexes slightly.

In some locations, the ground can move vertically by...