pquade

Mun 0° Longitude Placement vs Moon - Theories?

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The Earth's Moon is tidally locked in place.  Its Prime Meridian (0 degrees longitude) is nominally the center of the side that faces Earth.

Kerbin's Mun is different.  Its Prime Meridian is rotated toward the prograde side of Mun by quite a bit.  I have a personal pet theory about why this might be, but I'm curious what anyone else thinks might be the reason.

My theory is for a low Mun orbit, it more or less marks the location of the place where you can best start your burn to get back to Kerbin IF you're orbiting in the prograde direction.  I can't think of any other possible reason, and I'm probably wrong about this, but I'm curious if anyone else has even considered the placement of Mun's Prime Meridian before.  I mean why IS it located where it is?

I'd love to hear from one of the devs if anyone from KSP wants to give some history on it.

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I think they made the Mun map, then decided what should face Kerbin, and didn't care about the internal number of the meridian because they never told it to the player.

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If I'm not mistaken, at one point the Mun had a different side facing Kerbin in an earlier version. They probably rotated it and didn't change the Prime Meridian to face Kerbin.

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I think that the main reason for Mün's and Minmus' orbit is that they work as easy targets for new players.

With Mün it's inclination takes that out of the equation when travailing to and from it.

With Minmus it adds the issue of inclination but due to it's low mass is more forgiving once you got the point.

One could argue that Duna and Dres is the same thing, but one grade higher ;)

 

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9 hours ago, Superfluous J said:

I think they made the Mun map, then decided what should face Kerbin, and didn't care about the internal number of the meridian because they never told it to the player.

The thing about Longitude is for any body which isn't tidally locked, its placement is pretty arbitrary.  On a tidally locked body though, it's definitely an intentional choice because the default would naturally be to have it face directly the parent body just like the real Moon.  They sort of had to care at a certain point otherwise they'd could potentially end up with the Armstrong Memorial on the far side as opposed to near side.

So the question remains, why place it where they did in this particular case?

4 hours ago, Curveball Anders said:

I think that the main reason for Mün's and Minmus' orbit is that they work as easy targets for new players.

Determination of Prime Meridian has nothing to do with that though and wouldn't affect that in any way.

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Posted (edited)
40 minutes ago, pquade said:

So the question remains, why place it where they did in this particular case?

 

40 minutes ago, pquade said:

 They sort of had to care at a certain point otherwise they'd could potentially end up with the Armstrong Memorial on the far side as opposed to near side.

 

Edited by DunaManiac

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5 hours ago, pquade said:

The thing about Longitude is for any body which isn't tidally locked, its placement is pretty arbitrary.  On a tidally locked body though, it's definitely an intentional choice because the default would naturally be to have it face directly the parent body just like the real Moon.

If they cared they'd have made it either a limb or the center line. 

Someone drew the Mun map. They mapped it to a sphere. They turned it a bit and liked it one way over any other. Rather than edit the map file, they just left the globe turned.

I see absolutely no reason to accept any other explanation than this one. It's the simplest and makes sense. Occam's Razor and all that.

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Posted (edited)
1 hour ago, Superfluous J said:

I see absolutely no reason to accept any other explanation than this one. It's the simplest and makes sense. Occam's Razor and all that.

So, even if one of the devs posted that you were wrong and had another explanation you'd see no reason to accept it?

Come on, man.  That's not how science works.

Edited by pquade

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Posted (edited)
13 minutes ago, pquade said:

So, even if one of the devs posted that you were wrong and had another explanation you'd see no reason to accept it?

Come on, man.  That's not how science works.

I never said that.

I didn't say "I can never see any other point of view."

I said "I currently can't see any simpler reason."

If you think your theory is more reasonable then hey, I can't convince you.

Here's an alternate theory. HarvesteR's mom's birthday was the digits of the rotation of the prime meridian from where it would normally be. That's at least as reasonable as "It's kind of close to where you'd burn to return to Kerbin."

Edited by Superfluous J

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Posted (edited)
11 minutes ago, Superfluous J said:

I said "I currently can't see any simpler reason."

No.  You said, "I see absolutely no reason to accept any other explanation than this one."  I specifically quoted it for a reason.

We have competing ideas about how it may have happened.  I admitted mine might (
probably even) be wrong, you seem to assume yours is the only correct answer.  Let's see if somebody else can come up with another idea before closing our minds entirely here.

BTW, have you even looked into the possibility my idea checks out?  Try it.  Be in low Mun orbit, prograde direction, and use something like Astrogator to create a return node.  See where it ends up being.

Meanwhile, there's literally no way we can check your idea since that would be completely based on a subjective standard.

Edited by pquade

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2 hours ago, pquade said:

No.  You said, "I see absolutely no reason to accept any other explanation than this one."  I specifically quoted it for a reason.

I apologize. I thought "without further proof" was assumed. As it was not, let me add it.

Without further proof (not speculation), I see absolutely no reason to accept any other explanation than this one.

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3 hours ago, pquade said:

No.  You said, "I see absolutely no reason to accept any other explanation than this one."  I specifically quoted it for a reason.

To be fair, I don't think "I don't see a reason..." is generally interpreted as "I will never change my viewpoint." but rather as "you'd have to come up with something really compelling that we haven't seen yet"

Mun is pretty old. I don't mean "billions and billions of years," I mean in the lifetime of the game, and introduced at a point where pretty much anything was added in an experimental way. The theory of the "burn meridian" is a charming theory. One might even argue it has merit. There's one very serious issue with it. Back when Mun was introduced, how would you know you're crossing the 0° meridian? Especially when it's no secret that Harvester's take on the game was always "fly by the seat of your pants, not by the numbers" - unless there's some recognizable terrain feature at 0° I just don't buy it.

I agree with 5th Horseman here; Occam's razor applies. They applied a texture map to Mun. Someone said "that looks stupid, why don't we rotate so we have those features facing Kerbin?" and the decision was made to implement that by rotating the moon.

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5 minutes ago, Kerbart said:

unless there's some recognizable terrain feature at 0° I just don't buy it.

Okay, but why "buy" the other theory either?  I mean, what is on the near side as a feature that makes it look "better"?  It's not like it duplicates the IRL Moon, so that's a no go.  "Looks better" is simply subjective here.  What can be argued looks better about any side of Mun?  It's not like it has a face or rabbit or the equivalent of Tycho.

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1 hour ago, pquade said:

Okay, but why "buy" the other theory either?

One makes sense ;)

1 hour ago, pquade said:

I mean, what is on the near side as a feature that makes it look "better"?  It's not like it duplicates the IRL Moon, so that's a no go.  "Looks better" is simply subjective here.

It being subjective doesn't mean it didn't happen. Someone with say-so just said so.

1 hour ago, pquade said:

What can be argued looks better about any side of Mun?  It's not like it has a face or rabbit or the equivalent of Tycho.

No one needed to argue anything. I imagine whomever did the art showed it to HarvesteR and he said to put it one certain way and that was it. It's not like you're going to argue with your boss over something that you don't care about.

Or maybe it was totally completely random. They loaded Kerbin and Mun in the game and the way they'd set up the Mun orbiting Kerbin, its surface happened to aim it that way. And later, if they ever changed that part they'd obviously rotate Mun because by then any other facing would look wrong.

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Posted (edited)

How are the Mun archs oriented?
Maybe their axes show some directions? Or their intersections mark some important points? Did anyone try digging for a treasure where they intersect?

What if take a rope, tie it to the Mun archs and let the Mun hang down?

Maybe there are some archs missing where they should be? What if add them there?

Edited by kerbiloid

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15 hours ago, Superfluous J said:

I see absolutely no reason to accept any other explanation than this one. It's the simplest and makes sense. Occam's Razor and all that.

The only other one I could think of (and wouldn't know how to verify) is that it might relate to the celestial coordinates at game start, t=0.

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Posted (edited)
12 hours ago, kerbiloid said:

What if take a rope, tie it to the Mun archs and let the Mun hang down?

Maybe there are some archs missing where they should be? What if add them there?

I think we can dismiss this being the as a result of a vector from existing arches since that would require one at the North Pole for latitude to work out.

If we moved into completely hypotheticals, we could in fact make it work out if we located one at the North Pole and rotated it, but again that seems highly unlikely as the original idea for the location of the Prime Meridian since even then you'd end up with 180° of ambiguity.

3 hours ago, Laie said:

The only other one I could think of (and wouldn't know how to verify) is that it might relate to the celestial coordinates at game start, t=0.

I'll have to look into this.  It could actually make sense if the Prime Meridian somehow ended up pointing directly at say, the Sun at game start.

Edited by pquade

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Posted (edited)
12 hours ago, pquade said:

Okay, but why "buy" the other theory either?  I mean, what is on the near side as a feature that makes it look "better"?  It's not like it duplicates the IRL Moon, so that's a no go.  "Looks better" is simply subjective here.  What can be argued looks better about any side of Mun?  It's not like it has a face or rabbit or the equivalent of Tycho.

Let me tell you a little story.

A long, long time ago, when I was only a young Kerbart and had aspirations, I went to college to become an engineer. At one of my internships I worked at a factory for kitchen countertops and medical furniture (side tables, etc). At one point we had to work on a new small table that, attached to a stand, could be put next to a nurse or doctor to put their gear on while working on a patient lying in bed. I was excited, because here I saw real design in action. Surely, my boss would whip out some tome of medical standards that described how far off the ground said table surface needs to be.

What followed was an eye opening disappointment in How Things Are Made. "Kerbart, come over here. Pretend you just inspected someone's ear with one of those scope things and now you want to lay it on our table... STOP RIGHT THERE!!!" As my hand was about to lay the pretend ear-scope on the pretend-table surface, my boss whipped out a tape measure and measured from the ground to my hand what the required distance was. That's your medical standard for table height right there...

On another occasion we made small serving trays as a Christmas gift for customers. I brought one home and my father was delighted to learn how we defined the intricate not-quite-an-ellipse-not-quite-an-oval shape. He'd love to learn from his future engineer son what the math was that was involved in such curves. "We traced a tupperware container" was my sheepish answer.

Moral of the story: don't always look for grand explanations of why things are the way they are. Sometimes the underlying reasons are shockingly ordinary.

Edited by Kerbart
pselling

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Posted (edited)
41 minutes ago, pquade said:

I think we can dismiss this being the as a result of a vector from existing arches since that would require one at the North Pole for attitude to work out.

I just used this method to calculate average coordinates of a set of cities.

P.S.
If I could "like" the prior post several times...

Edited by kerbiloid

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Posted (edited)
1 hour ago, Kerbart said:

Moral of the story: don't always look for grand explanations of why things are the way they are. Sometimes the underlying reasons are shockingly ordinary.

And yet in both of your examples there were actual underlying reasons as opposed to supposition or randomness.  I'm not necessarily looking for the answer to the grand unified field theory here; just why this particular aspect of the game differs from what one would expect.

 

Edited by pquade

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