If everything goes according to plan for the Chinese city of Chengdu, by the year 2020 they will have sent an artificial moon with which they plan to replace the lampposts. That being the case, doubt may arise. What would happen if the Earth had two moons instead of one?
The short answer: nothing good. The reasons are several, as the children of Science Insider explain in their last piece. Imagine that the identical identical twin of the Moon approaches and is trapped by the gravity of the Earth. As it is established in orbit, halfway between the planet and our original moon, it would violently pull off the oceans.
Let's think that in the real world, this is how our original Moon helps generate tides. Therefore, the second moon would amplify the effect. Causing maximum tides that would be 6 times higher, eroding the coasts and flooding many of the largest cities on the planet, such as New York, Singapore or London.
However, not all destruction would occur on Earth. That combined pull of the planet and the original moon would also give a pull to the second moon. The second moon would be caught in a battle between Earth and the original moon.
The gravitational movement back and forth from both ends would distort the surface of the second moon and cause a monstrous volcanic activity, flooding the surface of the second moon with rivers of red hot lava.
And even then, it's not the end of the show. At that time, our moon would be spiraling away from the Earth at an average of 3.8 cm per year. At the same time, it attracts the Earth slowing down the rotation of the planet. What is really extending our days in about 1 second every 40,000 years.
It may not look like much, but with two moons it would accelerate this process even more. In millions of years the day would have grown by 16%, which would mean that the day lasts more than 28 hours. And although a little extra time in the day may sound good, here's the big problem: the extra moon would be diverted to the current Moon.
This being so, after millions of years the two moons would be destined to collide irremediably. The impact would be so great that it would tear apart the core of the moons. The lava would sprout from its center, something like an egg dripping in space. Meanwhile, the debris would be fired at high speed, and some of them would inevitably hit the Earth, forming huge craters kilometers wide.
Not only that, what does not hit the planet would be trapped by the gravity of the Earth. Forming a kind of debris ring around the equator. Something similar to the rings around Saturn, although not for long. In a few years, those pieces would be grouped into a single giant body.
At this point of the apocalypse, it is possible that any life that has survived the previous events will call it … Luna. [ScienceInsider]