Indeed, moon is moving away from earth, BUT WHY?

Last updated on October 10th, 2020 at 07:57 pm

moon-is-moving-away-from-earth
Credit: NASA Space Place

Are we really going to lose our only moon? Well, YES. We will. Moon is moving away from earth. Yeah, you heard me right. I am not lying. But, there is a catch. I mean, how fast is the moon moving away from earth is where things get complicated.

In this article, I will try to present a clear picture about the moon and why in actuality the moon is drifting away from earth, OR, perhaps not. So buckle up.

Today, the ride I am about to give you is a little tricky. So, let’s start the journey. Here are some things I will discuss in detail…..!!!!!

  1. Are we really going to lose our only moon?
  2. Why the moon is moving away from earth?
  3. Possible effects due to the moon’s disintegration from earth
  4. Earth could fall apart
  5. A day on earth is getting bigger and bigger
  6. Seasons on earth will be drastically affected
  7. May be total disintegration won’t happen

 

Are We Really Going To Lose Our Only Moon?

As I said in the introductory paragraph, it’s a tricky business. I mean, the process of the moon’s drifting away from our motherland is quite slow. If I talk about the rate at which the moon is drifting away is almost negligible in terms of human perception.

Well, as per the measurements done by laser reflectors left during the Apollo mission, with each passing year, our moon is moving away from earth at the rate of approximately 3.78 cm.

So, I can say that there could come a time when we won’t be seeing the closest object in the night sky. As per the theoretical calculation is concerned, it would take billions of years for total disintegration to happen in actuality.

Therefore, there is no reason to worry now. I mean, you will see the moon every day in the night sky. Just don’t take it for granted forever.

Perhaps, maybe you should be giving a little extra thought about the obvious reason behind that why is the moon moving away from Earth?

 

Why The Moon Is Moving Away From Earth?

Frankly speaking, we don’t know why exactly the moon is moving away from earth. In other words, there could be several reasons behind it.

Like, maybe the moon is disintegrating because of the Hubble’s Law Of Cosmic Expansion. Another reason or perhaps the more obvious one is due to the tidal interaction between earth and its one and only moon.

Tidal effects or tidal forces are the forces that generally arise due to the gravitational pull of a body on the other one. For example, high tide and low tides occur in oceans due to the gravitational influence of the moon on the earth’s surface.

moon-is-moving-away-from-earth-due-to-tidal-forces
Credit: Toonpool

During tidal interaction, the moon’s gravity pulls earth toward itself. As a consequence, there is a substantial decrement in the rotational kinetic energy and angular momentum from the earth’s spin. Hence, further slowing the earth’s rotation.

In order to conserve the whole effect, earth in return exerts a gravitational pull on the moon’s surface. Therefore, transferring the lost rotational kinetic energy and angular momentum to the moon.

Hence, expanding the moon’s orbit around the earth. Well, that’s the beauty of nature itself. In other words, the whole tidal interaction is totally conserved.

 

Possible Effects Due To The Moon’s Disintegration From Earth

Ever wondered, why does the earth need the moon? Well, there could be so many bizarre possible effects due to the moon’s disintegration from the earth. Some of them are explained in detail below…!!!

 

Earth Could Fall Apart

Indeed, it could happen in the far coming future. As per the governing laws of the earth-moon system, both of them are balancing each other’s rotational axis. There are certain chances that if the moon has drifted to its threshold, it could cause disastrous things on earth.

I mean, maybe earth could fall from its elliptical orbits. And if that happens, the earth will (and it will) spiral into the sun meeting its ultimate fate.

destruction-of-earth
Earth could possibly lose its elliptical orbit and spiral down into the sun/Credit: Coil

Another possibility is that maybe earth would cease to rotate on its axis. I mean, I have explained earlier that earth rotation is slowing with each passing year.

Well, if that happens, it could cause devastating consequences on earth. Like, the side facing the sun will never see night. on the other hand, the side opposite to the sun will never see daylight. I mean can you imagine??

 

A Day On Earth Is Getting Bigger And Bigger

Yup. You heard me right. As the moon is moving away from earth, a day on earth is getting bigger and bigger. In other words, the earth’s rotation is slowing with each passing year.

Well, if I talk about the current timeline, the earth takes approximately 24 hours to complete one cycle on its axis. Just to give you a glimpse that how slow the moon is disintegrating from the earth.

In order to make a 24 hour a day to 25 hours a day, it would take approximately 15 million years to do so. MIND BLOWN.

On the contrary, Atomic clocks have also calculated that a day on earth is getting longer and longer by 15 microseconds per year.

Pluto-Charon-system-giff
Pluto-Charon system displaying doubly tidal locking/ Credit: Wikimedia Commons

Theoretical physicists have calculated that the moon will continue to disintegrate until the orbital period of the moon around the earth becomes 47 days.

In a similar fashion, the earth’s spin would become one rotation every 47 days. And when that happens, the earth and the moon will be doubly tidally locked with each other.

Meaning, both Earth and moon will see each other’s same face permanently. The best example of a doubly tidally locked system is the case of Pluto and its moon Charon.

Let’s Go Back In Time

Just for my curiosity, suppose we simply reverse the timeline, we could even calculate the earth’s spin in its younger days.

Meaning, there could be a time when the earth was moving fast enough that it would have taken only 1 or 2 hours to complete a cycle on its axis.

In more simple terms, there would be a time in the very far distant past when a day on earth will be 1 or 2 hours a day. Currently, we can say that the earth and the moon are singly tidally locked with each other.

That’s why we can’t see the far side of the moon. (For more detailed information related to the single tidal locking and the dark side of the moon, you can check this article). I m sure you will love it.

 

Seasons On Earth Will Be Drastically Affected

Again, for the same reason, seasons on earth will be drastically affected. The reason i.e the moon is moving away from earth could also affect seasons on earth.

Well, if you don’t know, the earth’s tilt is the reason for the seasons. The angle of the earth’s axial tilt is approximately 23.4 degrees.

Well, there is no physical definition for the reason behind the earth’s tilt or its obliquity. In fact, there are so many distinct controversial hypotheses regarding the same.

why-moon-is-moving-away-from-earth
a simplistic representation of the fact that how was the moon made and how earth got its axial tilt/Credit: Wikimedia Commons

Well, one of the critically acclaimed hypothesis is the Giant impact hypothesis. According to this hypothesis, around some 4.5 billion years ago, young earth collided with mars sized planet resulting in an axial tilt of 23.4 degrees.

Moreover, this collision is also held responsible for the formation of the moon. On the other hand, physicists claim that the moon is responsible for maintaining that 23.4 degrees of axial tilt.

And, with the moon gone from earth’s night sky could seriously change this earth’s tilt. Hence in return, causing devastating changes on seasons on earth.

Well, if you don’t know, just because of the earth’s tilt, when there is summer in the northern hemisphere, simultaneously, there is winter in the southern hemisphere.

Meaning, currently in India (northern hemisphere), right now there is a summer season. On the other hand, in Australia (southern hemisphere), there is a winter season.

Let’s Go To The Future

As I said, this disintegration process could take billions of years to reach its zenith. And when that happens, life on earth will definitely extinct. Or, perhaps not.

There are chances that the whole of the northern hemisphere will see sunlight forever. On the contrary, the whole of the southern hemisphere will never see a glimpse of sunrise. OR VICE-VERSA.

must read, 8 Lunar Phases Of Moon – From New Moon To Full Moon To New Moon

As far as we humans are concerned, with our technological advancement; we may survive. I mean, to protect our self from extra heat we could use the super-advanced air conditioner.

Similarly, we could use a super-advanced heater to protect ourselves from the harsh winter. Or, simply we may adapt to live in extreme harsh summer as well as in harsh winters.

Well, what about the animals? I mean, they are not as frequent in the adaptation process as compared to humans. Therefore, all the animals of the earth could be wiped out. OR MAYBE NOT.

I mean, maybe by that time; animals too could become an intelligent species just like us humans. Ahh. Now that’s something new for today. What do you think? Is it possible?

 

Maybe Total Disintegration Won’t Happen

YUP. You heard me right. Maybe total disintegration won’t happen. I mean, from now; it will take billions of years to happen. As a result, something else could happen.

One of the possible contenders is that our sun will engulf both earth and moon much before the moon’s total disintegration from the earth.

In his current phase, our sun is considered as a G-type main-sequence star. Meaning, the sun is currently fusing hydrogen into helium in its core.

In that case, if you don’t know, after its stellar death; our sun is destined to become a white dwarf. (well, our sun could never become a neutron star or simply a black hole simply because it does not meet the certified criteria).

As per heliophysics, when the sun’s core will run out of its nuclear fuel, it will gravitationally collapse under its own weight; giving birth to a white dwarf.

Just before becoming a white dwarf, the sun will become a red giant expanding its horizon that will eventually engulf the moon and earth much before their mutual disintegration.

Therefore, maybe the total disintegration of the earth-moon system may actually not happen.

 

Conclusion

In my view, neither of them is going to happen. I mean, for the moon to totally disintegrate from the earth, it will take approximately 50 billion years.

On the other hand, for our one and only sun to become a red giant and swallow both earth and moon, it will take approximately 5 billion years from now.

Therefore, my concluding thought is that whether we will or we will not lose our only moon is too hard to be predicted. Simply because we are talking about things that could or could not happen in the very far future that we won’t ever see.

Or, maybe tomorrow or after 1 week or a year, the earth could be destroyed by aliens. Well, who knows? What do you think? I mean, definitely, the moon is moving away from earth.

But we can’t just simply calculate the moon’s eventual fate. Any ideas about it? Feel free to enlighten me. I am all ears. Plus because of the pandemic situation, I am totally available. I am waiting for your thoughtfulness.

That’s it for this post. If you like this article, share it if you like, like it if you share it. You can also find us on Mix, Twitter, Pinterest, and Facebook.

About Atul Sinha

I am a mechanical engineer by profession. Just because of my love for fundamental physics, I switched my carrier, and therefore I just completed my postgraduate degree in physics. Right now I am a loner (as like ever) and a Physics blogger too. My sole future goal is to do a Ph.D. in theoretical physics, especially in the field of cosmology. Because in my view, every part of physics comes within the range of cosmology. And I love traveling, especially the Sole one.

Leave a Reply