Artwork by Joshua Venturo
Tides. They suck water out to the deep, out of sounds, and through inlets; they expose the rocks encrusted with life; they surge back up over land. All this pulling, surging, moving of tons of water, is controlled by the moon, which is controlled by God. It is He Who keeps life going—and we get to study how He decided to do it!
Tides are caused by the gravitational pull of the moon (gravity is what pulls a book onto the floor when you drop it). The earth has gravity and so does the moon. Since the moon is so close to the earth, its gravity pulls the water from the oceans toward itself, creating a bulge. Let’s say you are standing on the shore. If the gravity of the moon is pulling straight up from where you stand, it will be high tide. The moon is pulling the water up the land. At low tide, the moon will be pulling from the middle of the ocean, sucking water off the land. High tide to low tide is about six hours. As the earth and the moon move, high tide will move with the moon. So, it takes high tide twelve hours to “move” around the earth.
The sun also pulls on the earth’s water, but it is not as strong. When the sun and the moon pull from the same direction, the result is a spring tide (spring tides don’t just happen in the spring). This is a very dramatic tide. A neap tide is when the sun and moon pull at right angles. This makes the tide stay mostly the same from high to low.
Now you know all about tides! We have learned how tides happen, as well as what spring tides and neap tides are! So next time you are at the beach, take note of the tides. You may even be able to find an inlet and see the tide pulling water out of a sound. God is so great to make us able to study His Creation!
Information from: Seligson, Sherri. Exploring Creation with Marine Biology. Anderson: Apologia Educational Ministries, Inc, 2005.