With a push in the opposite direction, the angular momentum decreases. This means that the overall rotation rate is small. The moon does not stop orbiting completely, but it is now orbiting so slowly that it acts like a rock falling towards the earth and almost hits it.
The best way to upset the Earth and the Moon is to completely freeze its orbit or to reduce the Moon’s velocity to zero (in the case of the Earth) in the language of physics. Once the moon stops orbiting, it will fall right on the planet, because gravitational force will pull it from the earth and increase its speed as it moves towards the planet. It’s basically like throwing a rock into the earth, except it’s so big that you can make a movie about it.
To accomplish this, you need either a big “mysterious” force or a push for a long time. (If there is an alien reading, please do not use it as a blueprint to destroy the Earth.)
Can the moon pull the earth’s ocean?
But an accident is not the only way that the moon can destroy us. At one point in the trailer, the moon appears to be so close that its gravitational force pulls the ocean from the planet’s surface. Could it really be?
Let’s start with the simplest case, where the moon and the earth are stationary and almost sensitive. It will look like this:
Now suppose I put 1 kilogram of water on the surface of the planet. Since that water has mass, it interacts gravitationally with the earth, pulling the water towards the center of the earth. But a gravitational force from the moon is also pulling in the opposite direction. Which ball will be bigger?
We can calculate both using the same universal gravitational force for the lunar orbit. For interaction with the earth, we will use the mass of the earth and the mass of water. (I picked 1kg to make it easier.) Distance (And) Will be from the center of the earth to the surface – it is only the radius of the earth. For interacting with the moon, I’ll use the moon’s mass and the moon’s radius (plus a little extra because they’re not quite touching).