Explanation of the Tides & Moon


Hi. I'm Sean Tvelia, and we're here at Suffolk County Community College to discuss the influence between the moon and the tides. To understand tides you need to understand a little bi about gravity. Now, gravity is an attractive force that is caused by mass. And simply said, the more massive an object is the more gravity it exerts on its neighbors. Now in the earth moon system, unlike the rest of the planets in the solar system, the moon is relatively large compared to our planet. And as a result it exerts a relatively large amount of gravity to earth's surface. That gravity causes the land and the waters to bulge in the areas directly beneath the moon. Now that bulge occurs on the side of the earth that faces the moon and waters are drawn towards the moon, we actually have another bulge that occurs on the other side of the planet directly away from the moon. All this goes on while the earth rotates beneath the moon. So twice a day areas of the earth are located beneath the moon and then later in the day, 12 hour later on the opposite side of the planet. So early on first they enter the tidal bulge of the moon and then as the earth continues to rotate the tides recede and then the earth enters the second area or the opposite side where the second bulge occurs beneath the moon. So when we look to understand the tides and the moon the tide are directly related to the gravity or the gravitational influence cause by the moon and we see that those tides not only affect the water ways but also affect the surface or the land areas that actually rise too. But the water being a fluid actually rises a greater amount and it's much more noticeable to us on land. And that is how the moon influences the tides.

Professor Sean Tvelia is an Associate Professor of Geology at Suffolk County Community College.