MYTH: The moon's gravity pulling on water causes the tides.

This is only partly true.

The moon does pull on ocean water, but that tug at any one point is about 10 million times weaker than Earth's gravity. It's really the interplay of gravity between the moon, Earth, and sun that creates a tidal force, and it's more of a "push" than a "pull."

Each molecule of water is pulled by the moon's gravity, but alone that acceleration is so weak it isn't noticeable. Because ocean water covers about 71% of Earth's surface and is connected as one liquid body, however, all of those tiny tugs add up to form a significant pressure — the tidal force.

Molecules of water near the poles are pulled mostly straight down, those on the face of Earth closest to the moon experience the strongest pull toward the moon, and those on the opposite side of Earth feel the weakest acceleration.

Together, these interactions form a pressure on seawater that generally directs it away from the poles and toward the equator, where it's strong enough to fight gravity to form two bulges: the high tides.

High tides stay put as the Earth rotates underneath them every day, and they follow the moon as it orbits Earth every 28 days. Low tides occur where the tidal force (or water pressure) is weakest, and dramatic tides can result where land and seafloor terrain funnel more seawater into one spot.

Smaller bodies of water, like lakes and pools, don't have noticeable tides because they lack enough liquid to create a pressure that can visibly overcome the pull of Earth's gravity.

The sun's gravity also affects the tides, accounting for roughly one-third of the phenomenon. When the sun's gravity counteracts the moon's, it leads to lower-than-average "neap tides." When the sun lines up with the moon, it triggers larger "spring tides."

Correction: An earlier version of this article mischaracterized the nature of tides.

Sources: PBS Space Time/YouTube, USGS