Tides are an astronomical affect that we see here on earth.
They are caused by the moon's gravity pulling on the oceans.
Ferrofluid and a magnet; the magnet attracts the iron in the ferrofluid and causes a "bulge" just as the moon attracts the water and causes a bulge in the ocean.
Newton was the first to describe tides scientifcally.
Recall Newton's Law of Gravitation: gravitational force is proportional to the mass of each body and inversely proportional to the distance squared between them.
There are actually two high tides a day; one occurs on the side of the earth nearest the moon, and the other on the opposite side.
The high tide on the near side is caused by the moon's gravity pulling the ocean toward it.
The high tide on the far side is caused by the fact that the earth itself is attracted toward the moon more strongly than the ocean on the far side of the earth. Practically speaking, the earth gets pulled out from underneath the far ocean.
Tides are not the same height day after day. That is because the sun also exerts gravitational forces on the earth's oceans.
Tides are highest when the moon and sun are aligned. These are called leap tides.
Proxigean tides are the highest leap tides and occur when the moon is at its closest point to the earth.
Tides are lowest when the moon and sun are at ninety degrees to each other. These are called neap tides.
