Using the interactive as a guide, explain why there are two high tides every day.

The reason there are two high tides every day is due to the gravitational pull of the moon and the rotation of the Earth. Here's a step-by-step explanation:

1. Gravitational Pull: The moon's gravity pulls on the Earth, causing the water in the oceans to bulge out in the direction of the moon. This bulge is what we experience as a high tide.

2. Earth's Rotation: As the Earth rotates on its axis, the area of the Earth directly under the moon (where the high tide is) changes. This rotation means that any given point on the Earth's surface will pass through both the high tide bulge and the low tide area (where the water level is lower because it's been pulled into the high tide bulge) in a 24-hour period.

3. Two High Tides: However, there's not just one high tide a day, but two. This is because there's also a high tide on the opposite side of the Earth from the moon. This happens because the Earth itself is also being pulled by the moon's gravity, but the water on the far side is being pulled less because it's further away. This causes another bulge and high tide on the far side of the Earth.

4. 24 Hour Cycle: The Earth takes about 24 hours to rotate fully, but the moon is also orbiting the Earth in the same direction. This means the Earth has to rotate a bit more than 360 degrees for the moon to be back overhead. This is why it's about 24 hours and 50 minutes between high tides, not exactly 24 hours.

So, the combination of the moon's gravity and the Earth's rotation results in two high tides each day.