Dive into gravitys role in the ebb and flow of ocean tides. Learn how the revolution of the moon around the Earth, Earth’s rotation on its axis, and even Earth’s revolution around the sun influence our tides.
Watch this animation to find out more about tides. Then answer the questions in the Take Notes box below.
Need help? You might want to check the definitions of specific vocabulary terms. In addition to the glossary words you’ve already learned, the terms high tide and low tide will also be used. You may pause the animation, rewatch it as many times as you like, and read the transcript.
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Gravity is the invisible force in our solar system that helps keep Earth revolving around the sun, and the moon revolving around Earth.
But the pull of gravity also influences the Earth beyond keeping things in orbit. Ocean tides are caused by the gravitational interaction between the Earth, moon, and even sun.
Due to some complicated –somewhat mind bending physics– gravitational forces at play do some counterintuitive things.
The gravitational pull of the moon causes the loose liquid layer of our planet (ocean) to bulge on both sides. As the Earth rotates on its axis throughout the day, this bulge stays bulged – which results in high tides and low tides on either side of the planet at any given time.
And to make things even more complicated, the sun adds its gravity to the mix too. When the moon lines up in its revolution with the sun and Earth which happens twice a month, there are higher high tides, and when the pull is at this angle (moon at perpendicular angle) there are lower high tides.
And all of this pushing and pulling and tidal activity is predictable because the movement of these main players are predictable.
So we can set our tidal calendars and our surf schedule to the pattern of gravitational forces.