How Celestia and Luna "Raise" the Sun and Moon

[Comet Tail 808]

_{<Twilight Sparkle>}
Good evening, everypony!

I'm Twilight Sparkle, and I'm going to clear up some confusion on what Celestia and Luna do to "Raise" the Sun and the Moon, based off of what I know from my studies.



First off, I've seen some crazy ideas about Celestia and Luna running some big conspiracy...



(Ha ha. Verrrrry funny... )


Well, Terra (Not Earth. That's your planet) does spin on it's axis to make day and night. Celestia and Luna don't literally spin the Sun and the Moon around Terra, that would take ridiculous amounts of power! But they do keep the sun and moon rising every day.

It doesn't make much sense at the surface...
But, allow me to explain a few things.



Tidal Braking:

First, a moon's gravity causes a tidal bulge in a planet's oceans, and a tiny bit in the land, too. But because the planet spins, that tidal bulge is moved away from the moon, but the moon pulls back on that tidal bulge with it's gravity.

So this happens:


This is what happens with your Earth and Moon.

But our Moon is a little different...

It orbits in the opposite direction as Terra spins. See, your moon is in a prograde orbit, mine is in a retrograde orbit.

Uhm. I need to explain orbits, don't I?

An orbit is when a body falls towards another, but it's going so fast sideways, it misses, but as it flies away, it's pulled back, and it misses again.

Your moon is pulled forward, as it goes faster it misses your Earth more and more, so it goes farther away.

Our moon is pulled backward, so it's slowed down, and it gets closer to our planet. Or it would, if it wasn't for Princess Luna.

Our moon is also in a highly elliptical orbit


Normally it's so far out that Tidal Braking doesn't do much. But periodically it swings in close, and when it does, Princess Luna gives it a little boost.

If Princess Luna didn't push on it, then in just a few thousand years, it would break apart, and later after that, come crashing down on Terra!



The Moon also slows Terra's spin just a little bit every year - just enough to make the day a little less than a second longer. Not much, I know, and honestly it wouldn't make much of a difference if Celestia didn't speed it up again...

But this isn't how Celestia "raises the Sun". This is just how Luna keeps the Moon in orbit.

And so there you have it, Luna "raises the Moon" we say, by keeping it from falling out of the sky! Which would end all life in the world...



How Celestia "raises the sun" is quiet different...

Here's what your inner star system looks like:


Highlighted in red is Jupiter's orbit. It doesn't get very close to Earth...

Now, uhh, this isn't to scale, but it shows how the gas giant planet in our solar system is in an elliptical orbit:

(Uhm. It's not very good but you get the idea... )

Remember how the tides on your world pull your moon along, causing it to drift out slowly?

Zeus, the gas giant here, pulls Terra along, or pulls it back, depending on where the two planets are in their orbit. But no matter what, left by itself, in just a few dozen years, our world would either crash into the sun, be launched into a craaazy orbit that we couldn't survive, or launched into eternal night by Zeus' gravity, because it swings in so much closer to Terra, than Jupiter does to Earth.

It's important to note, that it wouldn't happen instantly. Each time Zeus swings by, it would change Terra's orbit only a little bit, and each time it swings by again, it would change it more and more, until finally either launching Terra into the sun, into a stable, but unsurvivable orbit (like really close to the sun), or into interstellar space and eternal night.

Every year, at the Summer Sun Celebration, Celestia has a power surge. That's what I had when I earned my cutie mark:


Except, unlike me as a filly, she can control it, and she uses her immense power to give Terra a little push back into it's normal orbit.

So because of her, the sun rises and sets every day. Without her, in only a few decades the sun would either become a tiny star, and the world would fall into eternal night, or the sun wouldn't set, and would burn the whole world.



And that's how Celestia "raises the sun".


And so there you have it! The Truth!


See, a little filly wouldn't be able to understand all that. Even lots of grown-up stallions and mares don't get it, so, often it's just simplified to: "They raise the sun and the moon".

Any questions?



_{[image credits: hot coco / Sarcastic Very Funny / Only One Second / bad drawing / The Truth / Any Questions?]}

Edited January 23, 2013 by Mattlight

[Ethan Pow 332]

yes, I agree as I have the same feeling on the matter as its pretty clear that celestia controls the gravitation forces of the sun to make the planet spin.

 

same with Luna but with the moon to keep it maintained.

[Parties like Pinkie 385]

How do you know how our solar system looks and works? Is Terra's system close enough to Earth's that you can observe it? If so, how come we haven't observed Terra's system yet?

[Starshine 16,330]

my god...

 

 

So, practically all they do was preserving and keeping their respective celestial bodies on track?

 

Then is it possible to have a solar eclipse on Equestria?

[Senor Citizen 516]

Actually, the way that the sun and moon rise is this guy shoots the sun out of a cannon at dawn, and the moon out of the same one at dusk. The way they move is the tragectory the cannon is on. Poof! Begone.

[Comet Tail 808]

yes, I agree as I have the same feeling on the matter as its pretty clear that celestia controls the gravitation forces of the sun to make the planet spin.

 

same with Luna but with the moon to keep it maintained.

 

</Twilight>

Thanks! There's lots of room for interpretation, but I think this is the best explanation for keeping physics and plot consistent. Though I wrote that Celestia doesn't really control the gravity of the sun, but rather adjusts Terra's velocity to keep it in it's orbit, so it's not flung somewhere else by "Zeus'" gravity

[Tank Legend 19]

Hay but eh ponies are called Earth Ponies and on the episode Hearth's Warming Eve the call their new land Earth.

[TheBronyHeart 2,640]

You basically in a few paragraphs talked about half the material we talked about in earth science relating to the sun and the moon last year O.o

[Comet Tail 808]

my god...

 

 

So, practically all they do was preserving and keeping their respective celestial bodies on track?

 

Then is it possible to have a solar eclipse on Equestria?

 

<twilight>

Uhm, yes. I guess so! Not to say it's not important, though. They really do raise the sun and the moon, because without them, the sun and the moon wouldn't raise! And solar eclipses are possible, yes, I've actually seen a few studying at the Canterlot school.

[credit]

 

Hay but eh ponies are called Earth Ponies and on the episode Hearth's Warming Eve the call their new land Earth.

 

Technically you are correct... But we just like to call it Terra... It's a more balanced and fair name. And it doesn't sound like we're talking about separatist Earth Ponies

Edited August 4, 2012 by Mattlight

[Solar Wind 595]

I always just said they use magic. Like Twilight does for levetation only they do it better cause they are the princess'...

[Colon Leftbracket 971]

Oh so this is what you were studying... hmm... and I just sat there, laughed, and made sarcastic remarks in the status update!

 

Well you certainly showed me up! Great job!

[Comet Tail 808]

I always just said they use magic. Like Twilight does for levetation only they do it better cause they are the princess'...

 

They do use magic. Telekinesis is a form of magic. Luna pushes on the moon with telekinesis, makes it go a little bit faster.

 

Celestia pushes Terra whichever way she needs to to keep it in the right orbit.

 

Levitation is a type of telekinesis, and it's all magic.

 

How do you know how our solar system looks and works? Is Terra's system close enough to Earth's that you can observe it? If so, how come we haven't observed Terra's system yet?

 

What do you mean you haven't observed us yet?

How am I using human technology if there aren't humans on Terra?

 

Uhm, we Equestrians can't observe Terra, but these humans have been sharing a lot of information with us. But human robotic telescopes can observe Terra.

 

I think Garret said you discovered our world back in year 2880 on your calender...

Or was it 2088?...

 

And you called it "Fortuna", anyways. We just call it the Sun

 

[This isn't a roleplay, here. I just decided to write the OP in Twilight's voice. But since you asked, I'm working off the fanon of a fanfic concept I have. Didn't want to disappoint ]

^{(credit1, credit2)}

Edited August 4, 2012 by Mattlight

[Tank Legend 19]

Yes we get time machines in the future or you do. Can't wait hahaha. It's 2012 so i think this proves time travel.

[Espionage 113]

 

This is a very comprehensive guide to the astronomy of Equestria. AND WHAT?! 2088? Or 2880?! So are you telling me that we're so backwards that we can't even detect a planet that can detect us?

[Comet Tail 808]

Yes we get time machines in the future or you do. Can't wait hahaha. It's 2012 so i think this proves time travel.

 

</Twi>

I wrote the OP in Twilight's voice just to make it a good read, but I've been coarsed into carrying this a lot farther than I ever meant to...

 

Quit breaking the fourth wall when you address Twilight! lol

 

 

This is a very comprehensive guide to the astronomy of Equestria. AND WHAT?! 2088? Or 2880?! So are you telling me that we're so backwards that we can't even detect a planet that can detect us?

 

 

[...]

Uhm, we Equestrians can't observe Terra, but these humans have been sharing a lot of information with us. But human robotic telescopes can observe Terra.

[...]

 

But we're getting sidetracked here... Let's try to stick to the topic at hand about this explanation for how Celestia and Luna raise the sun and the moon.

[RBDash 176]

I prefer the explanation that Equestrian-planet-land is flat. Makes it easier, doesn't put Equestria in such a cataclysmic position if the princesses were to leave/die/enter a coma/etc, and allows Luna control over the stars (since they're just lights in the sky in a flat earth).

[Comet Tail 808]

I prefer the explanation that Equestrian-planet-land is flat. Makes it easier, doesn't put Equestria in such a cataclysmic position if the princesses were to leave/die/enter a coma/etc, and allows Luna control over the stars (since they're just lights in the sky in a flat earth).

 

Well, while that might work canonically, I can't really accept that explanation because that makes space travel impossible

 

Oh, and this: Astromare costume:

 

 

 

No astronauts without space travel, and no space travel without a round planet.

[Twilight Yagami 16]

Honestly, I just figure that in this world the earth is flat; as our world was believed to be back then. Especially sense it was believed that

Tartarus existed at the edge of the world.

[Comet Tail 808]

Honestly, I just figure that in this world the earth is flat; as our world was believed to be back then. Especially sense it was believed that

Tartarus existed at the edge of the world.

 

Actually, that's just a common misconception. They've actually known the Earth was round for hundreds and hundreds of years.

 

/ Looked it up:

First idea dates back to 600 BC. It was a given by 300 BC. In the early 1500's Magellan circled the globe, practically proving it was round.

 

But as early as the dawn of time, you could prove it was round this way: Shadows.

 

On the longest day of the year, closer to the equator, the shadows will be smaller, and at further latitudes, shadows will be longer

 

And anyways, in the sailing ages you couldn't navigate with a sextant unless you know the Earth's round. They navigated by the stars, because by using how high different stars are in the sky at different times, you can determine your latitude and longitude.

 

We've seen old film, but with sound in the show, X-rays, plastics, Twilight's lab machine and other such tech. Also given Flim Flam's "mode of transportation", the show appears to be on average around 1910 in terms of technology, though some fields such as material science and medicine are a few decades ahead, and some fields such as transportation are a few decades behind.

Edited August 4, 2012 by Mattlight

[Music Chart Fan 818]

First, you did an outstanding job with this post. You obviously put a lot of work into it, and the in-character explanations and pictures really make it more entertaining to read. By the way, I laughed at the comic about Twilight being a "heretic," even if Twilight didn't find it funny.

 

Any questions?

I have seen in the fanon at least, if not the canon, that Celestia "raising the sun" and Luna "raising the moon" are daily rituals. This doesn't seem to fit with your explanation of Celestia's and Luna's duties only being performed on occasion. Do Celestia and Luna do anything to "raise" the sun and moon on a daily basis? Do they fake daily rituals to keep the uneducated plebeians happy? Or am I wrong to suggest that daily rituals happen at all?

 

Celestia and Luna don't literally spin the Sun and the Moon around Terra, that would take ridiculous amounts of power!

If this is true, why is it less ridiculous that Luna gives the moon an occasional "push" and Celestia moves the orbit of an entire planet? Moving the sun is too much, but moving a planet is okay? Controlling the orbit of the moon around the planet is too much, but giving the moon a "push" is okay?

 

Of course, assuming that the laws of thermodynamics and conservation of mass and energy are still applicable, where does the energy to move a moon and a planet come from? How is this massive amount of energy gathered, contained, and harnessed by a single pony?

[pactor 29]

too confusing did'nt read. Anyway I always just thought that Celestia and Luna used a giant sling shot to raise the moon. considering the science in fim it would probably work.

SCIENCE!!!

[Comet Tail 808]

First, you did an outstanding job with this post. You obviously put a lot of work into it, and the in-character explanations and pictures really make it more entertaining to read. By the way, I laughed at the comic about Twilight being a "heretic," even if Twilight didn't find it funny.

Thanks. Lol, she probably would've thought it was funny if, you know, it wasn't her being executed by someone she loves and looks up to to keep power while being heckled by her extremely close friends...

 

I have seen in the fanon at least, if not the canon, that Celestia "raising the sun" and Luna "raising the moon" are daily rituals. This doesn't seem to fit with your explanation of Celestia's and Luna's duties only being performed on occasion. Do Celestia and Luna do anything to "raise" the sun and moon on a daily basis? Do they fake daily rituals to keep the uneducated plebeians happy? Or am I wrong to suggest that daily rituals happen at all?

Twice, in the series opener, and in the "Cutie Mark Chronicles", S1E23, it's called "The Summer Sun Celebration", and in the first episode, IIRC, it's mentioned that it happens on the summer solstice, so once a year for Celestia.

 

Not much is mentioned about Luna's ritual.

 

The idea that it happens every day can only be deduced if you consider it fact that they directly raise the sun and the moon "sky is a dome" style, so it's a circular argument.

 

If this is true, why is it less ridiculous that Luna gives the moon an occasional "push" and Celestia moves the orbit of an entire planet? Moving the sun is too much, but moving a planet is okay? Controlling the orbit of the moon around the planet is too much, but giving the moon a "push" is okay?

[twilight]

 

Let me work this math for you...

 

The equation for centrifugal force is:

a = v^2/r

 

The mean distance to sun is:

1.496e11 m

 

That's the radius of a circle that the sun must trace every day, which is 939,964,521,954 m in circumference, from these numbers.

 

There's 86,400 seconds in a day (24 hours, that is).

 

So the sun's velocity would have to be 10,879,219 m/s! (speed of light is about 300,000,000 m/s, btw)

 

So if my equation is right, the centrifugal acceleration from the sun is:

791 m/s^2

 

Now, let's find the amount of energy per second, and thus power, this requires...

 

KE = 1/2 * m * v^2

 

Mass of sun = 1.9891e30 kg

 

And our power is 6.2227103855e35 Watts

= 6.2227103855e23 TW

= 6.2227103855e11 Yottawatts (YW)!!!

= 622,271,038,550 YW!

 

I would check to make sure this is more power than the human race has ever consumed, or do all kinds of research...

 

But I think you already understand that's a lot of power for one pony to be putting out 24/7...

 

By contrast, changing a near-earth sized planet's velocity by a few tens or hundreds of m/s once a year takes very little energy. How much power entirely depends on how long she takes to do it, of course.

 

Of course, assuming that the laws of thermodynamics and conservation of mass and energy are still applicable, where does the energy to move a moon and a planet come from? How is this massive amount of energy gathered, contained, and harnessed by a single pony?

 

Well, you've seen our telekinesis, right? It's just telekinesis, on a really big scale...

 

But it's still something we unicorns do all the time.

 

It took a very long time, and we're still not entirely sure, but it's commonly accepted that our telekinesis works by selective collapse of quantum states.

 

It's natural that humans, without magic, would think it's impossible to control the collapse of quantum states, but by using our magic, we can play probability in quantum mechanics. When we do telekinesis on something, instead of the atoms zipping around and bumping into eachother, their speed is collapsed in such a way that many of them move a certain direction, causing the object to move.

 

It's just an idea, though. It's kinda almost impossible to really put it to the test, but we think that's how it works, and how consciousness attaches to the body...

 

Conservation of energy is preserved: thermal potential energy is transformed into kinetic energy.

 

But objects have enough thermal energy that it's almost impossible to tell they cool off at all, and the air is enough to keep them from getting really cold if you levitate them against gravity for a long time.

 

[credits: 1, 2, 3.]

Edited August 14, 2012 by Mattlight

[Music Chart Fan 818]

Thanks for your responses so far, Mattlight.

 

By contrast, changing a near-earth sized planet's velocity by a few tens or hundreds of m/s once a year takes very little energy. How much power entirely depends on how long she takes to do it, of course.

All right, I have some numbers of my own to work out here. Feel free to correct me if necessary.

 

How much power would it take to adjust the velocity of Earth by, say, 30 m/s?

 

Earth orbits the sun at a velocity of 29,800 m/s. So let's say that the velocity of Earth has to be changed from 29,770 m/s to 29,800 m/s.

 

mass of Earth = 5.97219E24 kg

 

KE₂ - KE₁ = 1/2 * m * (v₂² - v₁²) = 1/2 * (5.97219E24 kg) * [(29,800 m/s)² - (29,770 m/s)²] = 5.336E30 J

 

Now assuming that Celestia takes one day (86,400 seconds) to accomplish this change in kinetic energy,

 

power = (5.336E30 J) / (86,400 s) = 6.176E25 W

 

Comparing this power to the power you calculated for rotating the sun around Earth (6.223E35 W), the power needed to adjust the velocity of the Earth is certainly several orders of magnitude less, but still in the realm of very large, I would think.

 

Conservation of energy is preserved: thermal potential energy is transformed into kinetic energy.

So, by your theory, the power needed to adjust Earth's velocity comes by converting thermal potential energy to kinetic energy. Where does this energy come from?

 

The total rate at which energy enters the Earth's atmosphere is estimated at 174 petawatts (174E15 or 1.74E17 W), which is mostly solar radiation, but includes geothermal and tidal energy.

 

As calculated earlier, we need 5.336E30 J of accumulated energy in order to adjust Earth's velocity by 30 m/s. If ALL of the energy entering the Earth's atmosphere every second were able to be collected and stored, it would take 3.067E13 seconds, or 971,870 years, to accumulate the necessary energy.

 

What if the necessary energy were to be extracted from the thermal energy of Earth? One estimate of the thermal energy of Earth I found was obtained by figuring an average specific heat of the Earth (860 J/kg*K) and multiplying that by an average temperature of the Earth (3000 K) and the mass of the Earth (5.97E24 kg). This estimate of the thermal energy of Earth came out to 1.5E31 J. Recall that we need 5.336E30 J of accumulated energy in order to adjust Earth's velocity by 30 m/s.

 

So, in order to adjust Earth's velocity by 30 m/s, more than 1/3 of the thermal energy of Earth would have to be extracted and used. This does not seem feasible to do every year.

 

So, I have to ask, where does the energy to adjust the velocity of Earth come from?

 

Furthermore, how is the extremely diffuse thermal energy and/or solar radiation collected and harnessed to adjust Earth's velocity? I understand that, theoretically, this is where the energy comes from, but it must somehow be collected and converted into useful kinetic energy.

Edited August 14, 2012 by Music Chart Fan

[Comet Tail 808]

Thanks for your responses so far, Mattlight.

 

You're welcome. I presume your thanks is extended to our one-horned two-eyed purple unicorn friend, too?

^{(Yeah, that was a reference to "One-Eyed One-Horned Flying Purple People-Eater")}

 

Thanks for taking interest.

 

All right, I have some numbers of my own to work out here. Feel free to correct me if necessary.

 

How much power would it take to adjust the velocity of Earth by, say, 30 m/s?

 

Earth orbits the sun at a velocity of 29,800 m/s. So let's say that the velocity of Earth has to be changed from 29,770 m/s to 29,800 m/s.

 

mass of Earth = 5.97219E24 kg

 

KE₂ - KE₁ = 1/2 * m * (v₂² - v₁²) = 1/2 * (5.97219E24 kg) * [(29,800 m/s)² - (29,770 m/s)²] = 5.336E30 J

 

Now assuming that Celestia takes one day (86,400 seconds) to accomplish this change in kinetic energy,

 

power = (5.336E30 J) / (86,400 s) = 6.176E25 W

 

Comparing this power to the power you calculated for rotating the sun around Earth (6.223E35 W), the power needed to adjust the velocity of the Earth is certainly several orders of magnitude less, but still in the realm of very large, I would think.

 

_[Twilight]

 

Actually, you got your math right, but made a teensy little mistake at the beginning...

 

We need to use a frame of reference where Celestia is initially stationary in order for this to work out correctly (An inertial frame of reference from Celestia).

 

(29,800 m/s)² - (29,770 m/s)² = 1,787,100

 

Which is very far from a mere 30², which is just 900.

 

So your final answer is (1,787,100 / 900) = 1,985.6666 repeating times larger than it should be.

 

And that's assuming she doesn't work with microbursts. She could use 900x less energy by moving it only 1 m/s, stopping, then moving it 1 m/s again.

 

30 * (0.5 * m * 1²) =/= 0.5 * m * 30²

 

So, by your theory, the power needed to adjust Earth's velocity comes by converting thermal potential energy to kinetic energy. Where does this energy come from?

 

The total rate at which energy enters the Earth's atmosphere is estimated at 174 petawatts (174E15 or 1.74E17 W), which is mostly solar radiation, but includes geothermal and tidal energy.

 

As calculated earlier, we need 5.336E30 J of accumulated energy in order to adjust Earth's velocity by 30 m/s. If ALL of the energy entering the Earth's atmosphere every second were able to be collected and stored, it would take 3.067E13 seconds, or 971,870 years, to accumulate the necessary energy.

 

What if the necessary energy were to be extracted from the thermal energy of Earth? One estimate of the thermal energy of Earth I found was obtained by figuring an average specific heat of the Earth (860 J/kg*K) and multiplying that by an average temperature of the Earth (3000 K) and the mass of the Earth (5.97E24 kg). This estimate of the thermal energy of Earth came out to 1.5E31 J. Recall that we need 5.336E30 J of accumulated energy in order to adjust Earth's velocity by 30 m/s.

 

So, in order to adjust Earth's velocity by 30 m/s, more than 1/3 of the thermal energy of Earth would have to be extracted and used. This does not seem feasible to do every year.

 

So, I have to ask, where does the energy to adjust the velocity of Earth come from?

 

Furthermore, how is the extremely diffuse thermal energy and/or solar radiation collected and harnessed to adjust Earth's velocity? I understand that, theoretically, this is where the energy comes from, but it must somehow be collected and converted into useful kinetic energy.

 

Like I said... thermal potential energy, or as you called it thermal energy. And it's used by controlled collapse of quantum superstates... Did you not understand me last time?

 

 

Let's say there's one atom. It could be moving with any velocity. However, once we measure it's velocity, it suddenly gets a velocity.

 

In uncontrolled quantum state collapse, then if you do this with millions of atoms, you'll get an even distribution of velocities, so the object as a whole has heat, but is holding still.

 

But unicorn telekinesis cause a majority of the atoms to collapse in one direction, so the object as a whole will be moving in that direction.

 

But that also means they aren't moving around and bumping into eachother as much, so there's not as much heat and thus conservation of energy is maintained in the object as a whole because thermal energy is exchanged with kinetic energy.

 

And, well, I guess that's it for this post. And you're welcome (Mattlight said you said thank you).

 

_{[credits: 1, 2, 3]}

Edited August 14, 2012 by Mattlight

[Music Chart Fan 818]

I've been trying to wrap my brain around your response for the last hour or so - not because you didn't explain it well, but because I think I was in the wrong mindset. I'll try to write my thought process in understanding this - please let me know if I'm thinking correctly here.

 

At first, I was envisioning increasing the velocity of Earth as like pressing the gas pedal in a car to increase its velocity, but the two are not analogous. A speeding car is constantly expending energy to maintain its velocity, since it has to counter energy lost to air resistance and frictional resistance with the road. However, Earth hurtling through space is not encountering any such frictional resistance. Therefore, Earth's state of motion through space is equivalent to a state of rest - no energy is expended to maintain the state. I think in this way the correct frame of reference for Earth's motion would be a frame of reference moving at Earth's velocity, since in this frame of reference, no energy is expended to keep Earth in its current state.

 

This explains why the correct v₂ and v₁ are 30 m/s and 0 m/s, as opposed to my previous numbers.

 

Achieving the adjustment in velocity with microbursts then makes sense in this paradigm of Earth hurtling through space with no frictional resistance. Whenever a new velocity is reached, this new state of motion is always equivalent to a state of rest - no energy is expended to maintain the new state. In the calculation of kinetic energy expended, this would make each new initial velocity zero. So indeed, a series of microbursts takes less energy than a single burst to achieve the same adjustment of velocity.

 

Finally, telekinesis works by taking the ordinarily random atomic/molecular motions (which on a macro scale we call thermal energy) and orienting them in a single direction. So there is no collecting or harnessing energy, but rather, orienting kinetic energy already present in the object.