Currently, the Moon is moving away from planet Earth at a speed of about 3.5 centimeters per year. However, according to scientists, there will come a day when the two will collide.
So how do we go from moving farther away, to then, somehow colliding? Well, according to researchers at Idaho University, it has everything to do with tidal friction. The Earth has held the Moon in its orbit due to a gravitational pull it has over the Moon. However, in turn, the Moon produces its own gravitational pull, that creates the tides of the ocean, in order to form a tidal bulge.
While the Earth is rotating, the bulge then stays just barely ahead of the moon. As this is taking place, the Earth feeds a slight amount of energy to the Moon, which causes it to go higher into orbit.
However, the rotation of Earth is predicted to eventually slow down to match the orbital period of the moon. When that takes place, Earth’s pull will begin tugging at the Moon, causing it to drift directly towards Earth.
“The final end-state of tidal evolution in the Earth-Moon system will indeed be the inspiral of the Moon and its subsequent collision and accretion onto Earth.” Jason Barnes, a planetary scientist at the University of Idaho explained to Forbes.
But, don’t run for the hills quite yet. Thankfully, by that point, the Sun would have already engulfed almost all of the solar system, meaning that we will already be gone by the time that happens. According to the researchers, it will be another 6.5 billion years before planet Earth and the Moon collide. The Sun is expected to go into its red giant phase in the next five billion.