Between 1991 and 1993, I wrote a series of articles for Astronomy magazine exploring a few different changes in Earth's astronomical environment and the likely results of those changes. In what follows, I present a sample scenario, some typical student responses, and a scientific analysis. In each what-if scenario, I make one change in Earth's environment and then consider the implications of that change. I call the new world Solon to emphasize its solo existence. To understand how Solon would differ from Earth, we need to know how the Moon is affecting Earth today and, working back in time, deduce its effects over the Earth's lifetime.
Tides occur because the gravitational force between two bodies decreases with distance.
Gravitation is the universal force of attraction between all matter. It holds astronomical bodies together and attracts different bodies toward each other. Because gravity tugs on nearby things more strongly than on distant things, the oceans closest to the Moon feel the greatest attraction to the Moon. Being fluid, these nearby oceans move upward in response to the Moon's pull, until there is a balance between the upward force from the Moon and the downward force from Earth. The high tide on the far side of the Earth occurs because these most distant oceans feel the least attraction to the Moon.