Water, the Moon, and the Gravity of the Situation

Recently, as I looked up into the night sky, it occurred to me what a remarkable partnership exists between the moon and water on Earth. It struck me as being even more amazing when I considered the vast amount of pull that this virtually waterless body has on most of the water on our planet. The moon, which is drier than any desert on Earth, to have the influence it has on our ocean water is incredible. To put it in even greater perspective, the moon—which is 238,900 miles away, and is approximately one-fourth the size and weighs 80 times less than the Earth—literally changes the way that of water moves across the Earth’s surface.

To give you a quick lesson on how the moon influences ocean tides, the moon has a great deal of gravitational pull on the Earth. This is what keeps the moon in orbit around our planet. Known as tidal force, this pull draws ocean water toward the direction of the moon, causing higher tides. The greatest tidal force occurs during a new moon, when the moon falls directly between the Earth and the sun, adding the sun’s gravitational pull to the “bulge” in ocean water. The second-highest tidal force occurs during a full moon, when the Earth is directly between the moon and the sun.

As the Earth makes its full revolution in the course of 24 hours, the oceans experience a cycle from the most direct to the most indirect exposure to the surface of the moon, thus creating the cycle from high to low tide, which occurs twice a day. Without getting into the complex reasons why, it’s also good to note that the moon’s influence on tides occurs on both sides of the Earth. Here is my favorite go-to resource for some great diagrams and a slightly more in-depth explanation.

You may ask, “So what?”

Other than having more or less beach space to spread out on during a vacation, what do the moon and subsequent tides really contribute to life on Earth? Quite a lot, it turns out. Here are the three biggest ways that tides—and the moon—impact our life.

  1. Ocean ecosystem: Tides churn up water, minerals and nutrients, as well as contribute to energy flow, on which things such as crabs, algae, snails, kelp and more survive. Without tides, these species would die off, depleting a vital link in the food chain for fish, birds and mammals.
  2. Global weather patterns: Tidal movements create ocean currents, and ocean currents distribute warm water and precipitation around the world. Without tides, scientists predict, temperatures and major weather events would be much more extreme on Earth.
  3. It’s also believed that the phases of the moon and the resulting tide levels impact everything from when sea turtles come ashore and lay their eggs to the fertility cycle and spawning of sea coral to increases in birth rates, crime and sleepless nights.

So, the next time you are out star gazing and see the moon, take a minute to marvel about the impact it has on us and the additional impact it could have if it really was made out of green cheese?