How does the moon's gravity affect Earth?

The moon's gravity affects Earth in several ways. It is responsible for the ocean tides, as well as the slight lengthening of the day on Earth. The gravitational pull of the moon causes the oceans to bulge out on the side facing the moon, creating high tide. On the opposite side of Earth, there is also a high tide because the solid body of Earth experiences a pull towards the moon that is greater than the pull on the water.

In addition to the tides, the moon's gravity also affects Earth's axial tilt. The gravitational pull of the moon helps to stabilize the Earth's axis, which is responsible for the regularity of the seasons. Without the moon, the Earth's tilt would be much more unstable, leading to extreme and unpredictable weather patterns.

Finally, the moon's gravity affects the Earth's rotation. The gravitational pull of the moon creates a torque on the Earth, slowing down its rotation rate over time. This effect is very small, however, and will take millions of years to significantly affect the length of a day.