How does tidal force work?

This sounds like I'm talking about the ocean tides. Well, I am but I'm more concerned with what this kind of force means to planets and moons.

Everyone that lives near an ocean is familiar with tides. Mariners must be concerned with tides so that they can navigate in and out of harbors and other low tributaries. Tides can flood a beach when they're high and expose vast amounts of sand when they're low. Some sea animals adjust their mating rituals or egg laying with the tides. But, the way that the moon causes tides is only one facet of tidal force.

Let's consider the moon, which is believed to have been formed when a planet the size of Mars collided in a glancing blow with the early Earth. The Earth and moon combination resulted, and it's the moon's gravitational attraction that causes tides. This attractive force causes the oceans to bulge out, and this force acts on all parts of the ocean. In other words the bulge in the oceans is both on the side facing the moon and the side away from the moon. Essentially, the moon is pulling the ocean out into an ovoid shape, resulting in ocean thinning at 90 degrees to the force vector that could be drawn between the Earth and the moon. This is one way to look at it.
Another way is to consider this tidal force is to think of the Earth and the moon rotating around a common center of mass point that's mostly near the Earth. Gravitational attraction provides centripetal force needed to remain in motion. This is why all parts of the Earth are subject to this tidal effect.

Tidal forces cause internal friction that results in heat, and heat energy bleeds off the kinetic energy of motion. The result of this is what happens when one body is too close to the primary body. Tidal friction causes the smaller body to be tidally locked to the primary body. This is what has happened with the moon. One side continually faces the Earth. That's why up until the Apollo moon missions we didn't fully know what was on the opposite side of the moon.

The reason this is important is that planets can be tidally locked to the star that they orbit. This is the case with mercury. Mercury is only 48 to 68 million kilometers from the sun and is tidally locked. One side is -173 C on the side away from the sun and 427 C on the side facing the sun.

Most moons in the solar system are tidally locked to the planet they orbit. It is this reason that Europa, which is locked to Jupiter, exhibits evidence of heated oceans below a thick layer of ice. Tidal forces cause the planet to squeeze and stretch as it orbits around Jupiter in an elliptical orbit and this causes frictional heat. Another example is Enceladus, a moon that orbits Saturn. It also has a relatively warm ocean under a layer of ice because of tidal friction.

Astronomers have to consider this tidal lock effect when they look at extraterrestrial planets that orbit around K-class and M-class stars that are smaller and much less luminous as our sun. Planets in the habitable zone must orbit closer and could be tidally locked to these stars. This would cause a problem with climate on these planets. One side would be too hot and the other side would be too cold. Life may only be possible at the terminal line between perpetual day and night. This is a subject that interests me because I think that life exists everywhere in the universe, but intelligent life may be rare and fragile. Hopefully, better observational techniques will allow us to know if life exists on these tidally locked planets.

Thanks for reading.