Our moon is 2,150 miles wide and orbits the earth at a distance of 384 thousand kilometers,
but since its formation, the moon has actually been moving away from the earth.
But what would happen if our moon suddenly came crashing down into the earth?
That’s what we’re going to talk about, right now on life’s biggest questions
Hello and welcome back to life’s biggest questions, I’m Charlotte Dobre.
Don’t forget to like and subscribe and let us know in the comments below a question you
have always wanted to know the answer to.
It is commonly agreed upon in the scientific community that the moon was formed when a
giant, Mars-sized planet, crashed into earth 4.5 billion years ago.
A chunk of the earth broke off and began to orbit around the bigger chunk.
Gravity crushed the chunk into a spheroid.
Interestingly, experts believe that the earth has seen many giant impacts, which resulted
in several moons being formed.
So what happened to these moons?
According to a study called, Moon falls, Collisions between the earth and its past moons, these
moons could have either crashed into the earth or been ejected from its orbit.
Furthermore, some experts believe that our current moon might crash into the earth in
the future, But not for about 65 billion years.
According to planetary scientist Dr. Jason Barnes, This is because the earth’s rotation
is going to slow down.
Currently, our moon is actually moving away from our planet at a rate of 3.8 centimeters
a year.
This is mainly because of the earth's tides.
The moon orbits our earth because of the earth's gravity.
But the moon is also large enough that it exerts a gravitational force on the earth,
causing the tides and the oceans to move, forming whats known as a tidal bulge.
The tidal bulge feeds energy into the moon, pushing it into a higher orbit.
According to Dr. Barnes, the earth's rotation will one day slow down, until it’s rotation
is the same as the moon’s orbital period.
When that happens, the moon will stop moving away from the earth.
Elsewhere in the solar system, in 6 billion years our sun is going to become a red giant,
which will push the moon toward the earth.
Barnes says that eventually, the moon will get so close, that it will begin to spiral
inward, dissipating its orbital kinetic energy in a spectacular collision and merger with
the earth.
Once the moon crashes into the earth, it will basically result in the earth turning into
a gigantic ball of magma.
Upon impact, about 10 to the power of 20 gigajoules of energy, or 10 to the 13 megatonnes of TNT
of energy.
This would melt all the ice caps, turn the oceans into vapor and wipe out all life on
earth.
The impact could be so powerful that it could cause the earth to break apart into large
chunks and change the angle of our poles, while at the same time, changing the spin.
Amazingly, though, after a few million years, the earth would have reformed, due to gravity,
without a moon this time.
It would have cooled and turned into a water planet, larger this time, with more gravity.
Then add a few billion years and life would begin to form again.
Another way that the moon could end up crashing into the earth, is if an object roughly the
same size and density of the moon, traveling at the same speed, hit the moon in the opposite
direction of its orbit.
This could stop the moon, knocking it out of orbit and send it falling into the earth.
The fall to earth might be slow, it could take millions of years.
But as it got closer, the inhabitants of the earth would no doubt experience chaos.
If the moon was even half the distance it is now from the earth, the tides would be
eight times as big.
Coastlines would move inwards, we’d lose a lot of coastal cities like new york.
The moon would slowly inch closer and closer, overwhelming our atmosphere, creating supersonic
winds.
Once the moon reaches the Roche limit, which if you didn’t know is where the gravity
of the earth is stronger than the gravity of the moon, pieces of the moon that are loose
would start falling to earth, causing meteor showers.
Closer still, The moon begins to scrape the surface of the earth, plowing into the crust.
This will wear down the moon gradually and may cause it to break up into large pieces.
At the same time, the moon will puncture the earth's crust, causing fault lines to open
up.
In this scenario, causing minimal damage, it may be possible for pockets of life to
survive on the planet.
A collision with earth in this way would allow for plenty of time for preparation.
But life on earth would cease to exist as we know it, humans may live out their existence
in bunkers far away from the impact.
But considering the moon would likely scrape across the equator, or near the equator, life
in the tropics would be nonexistent.
For now, I’m Charlotte Dobre, and you’ve been watching life’s biggest questions.
If you want to go on an IO binge, check out the playlist on the screen, biggest what-ifs.
Turn on notifications by clicking the bell, and we’ll see you in the next video.