What causes tides on Earth?

• A. The Moon's gravitational pull creates tides
• B. Solar wind
• C. The Moon's phases
• D. The Sun's heat only

Answer: (A)

Tides are produced by gravity. The Moon’s gravity pulls on Earth’s oceans, stronger on the side closest to the Moon and weaker on the far side, creating bulges on opposite sides of the planet. As Earth rotates, those bulges move under different places on the surface, causing high tides and low tides daily. The Sun also exerts gravity and can strengthen or weaken tides depending on alignment, but its effect is smaller because it’s much farther away. Solar wind and Moon phases aren’t responsible for tides, and solar heating doesn’t cause them. So the Moon’s gravitational pull is the primary cause of tides.