# Thoery of Relativity and the Moon Landing
**URL:** https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886
**Category:** Factual Questions
**Created:** [April 18, 2008, 1:59pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886 "2008-04-18T13:59:19Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@Philster](https://boards.straightdope.com/u/Philster)
#### Post date: [April 18, 2008, 1:59pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886/1 "2008-04-18T13:59:19Z")
I recall that on several occasions, when the Theory of Relativity (ToR) was discussed, someone explained the moon trip/landing calculations and how some calculations were made possible by the ToR…or maybe the adjustments help confirm some parts of the theory.
I have a decent understanding of both the Special and General Theory, but am I ‘misrembering’? If not, is there a factual answer?
How does the ToR fit into the calculations and success of the moon trip/landing? Or how do the calculations tie back to the ToR and offer proof?
Hope I make sense today! 🙂
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### Author:  [@Napier](https://boards.straightdope.com/u/Napier)
#### Post date: [April 18, 2008, 2:05pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886/2 "2008-04-18T14:05:30Z")
I don’t know but doubt that ToR was needed to do the moon trip. It might be that some measurements made during the trip provided a check on ToR, but at the velocities and distances involved I bet Einsteinian and Newtonian relativities were not importantly different.
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### Author:  [@friedo](https://boards.straightdope.com/u/friedo)
#### Post date: [April 18, 2008, 2:10pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886/3 "2008-04-18T14:10:38Z")
As far as I know, no manned spacecraft has ever required relativistic calculations for navigation – Newtonian mechanics has always been accurate enough.
One interesting factoid is that the GPS satellites must take both special and general relativity into account to maintain their extremely precise clocks.
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### Author:  [@bibliophage](https://boards.straightdope.com/u/bibliophage)
#### Post date: [April 18, 2008, 2:49pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886/4 "2008-04-18T14:49:57Z")
Various [Apollo missions](http://en.wikipedia.org/wiki/Lunar_laser_ranging_experiment) and unmanned Soviet missions placed reflectors on the moon, which have been used to confirm the predictions of General Relativity. Could that be what you’re thinking of?
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### Author:  [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)
#### Post date: [April 18, 2008, 4:10pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886/5 "2008-04-18T16:10:18Z")
Dunno about the moon landings, but …
[http://relativity.livingreviews.org/open?pubNo=lrr-2003-1&key=BEM77](http://relativity.livingreviews.org/open?pubNo=lrr-2003-1&key=BEM77)
"The Global Positioning System (GPS) uses accurate, stable atomic clocks in satellites and on the ground to provide world-wide position and time determination. These clocks have gravitational and motional frequency shifts which are so large that, without carefully accounting for numerous relativistic effects, the system would not work… "
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### Author:  [@mlees](https://boards.straightdope.com/u/mlees)
#### Post date: [April 18, 2008, 4:14pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886/6 "2008-04-18T16:14:18Z")
General Relativity helped explain an anomaly in Mercury’s orbit: [Tests of general relativity - Wikipedia](http://en.wikipedia.org/wiki/Tests_of_general_relativity#Perihelion_precession_of_Mercury)
Perhaps your remembering that?
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### Author:  [@Ludovic](https://boards.straightdope.com/u/Ludovic)
#### Post date: [April 18, 2008, 4:27pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886/7 "2008-04-18T16:27:53Z")
GPS has to use both general and special relativity to keep its extremely accurate clocks accurate.
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### Author:  [@Voyager](https://boards.straightdope.com/u/Voyager)
#### Post date: [April 18, 2008, 5:25pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886/8 "2008-04-18T17:25:17Z")
I suspect the lack of accuracy in position and velocity overwhelmed any errors from not computing things taking relativity into account. Especially the landing. They used radar to figure out how far away the surface was, not relativistic reckoning from Earth!
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### Author:  [@Tuckerfan](https://boards.straightdope.com/u/Tuckerfan)
#### Post date: [April 18, 2008, 6:30pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886/9 "2008-04-18T18:30:41Z")
I’m not sure, but I think that GPS satellites use Special and General Relativity in order to determine someone’s posistion.
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### Author:  [@Contrapuntal](https://boards.straightdope.com/u/Contrapuntal)
#### Post date: [April 18, 2008, 6:34pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886/10 "2008-04-18T18:34:59Z")
[QUOTE=Tuckerfan]
I’m not sure, but I think that GPS satellites use Special and General Relativity in order to determine someone’s posistion.
[/QUOTE]
Hard to say. It’s only a factoid at this point.
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### Author:  [@MrSquishy](https://boards.straightdope.com/u/MrSquishy)
#### Post date: [April 18, 2008, 6:38pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886/11 "2008-04-18T18:38:36Z")
Hold on a second.
I thought I heard somewhere that GPS has something to do with general and special relativity. Is that true?
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### Author:  [@Xema](https://boards.straightdope.com/u/Xema)
#### Post date: [April 18, 2008, 7:07pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886/12 "2008-04-18T19:07:28Z")
[QUOTE=MrSquishy]
I thought I heard somewhere that GPS has something to do with general and special relativity.
[/QUOTE]
I doubt you would have heard that here.
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### Author:  [@Napier](https://boards.straightdope.com/u/Napier)
#### Post date: [April 18, 2008, 7:20pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886/13 "2008-04-18T19:20:59Z")
GPS does need to account for both special and general Einsteinian relativity, as its timekeeping needs to be much more accurate than ignoring them would allow - ludovic mentions this above. But it is not as though it uses some special feature or aspect or behavior or trick of these relativities - only that ignoring them would introduce a large error. And GPS doesn’t rely on Einsteinian relativity, it only has to include its effects in calculations. If somehow Newtonian relativity had been nearly correct enough, GPS would do fine without Einsteinian relativity.
This is in contrast with, say, the astronomical study of gravitational lensing. If it weren’t for Einstein’s general relativity, this study would not work at all.
I keep hearing faint, windy noises, sort of swooshlike, but not swooshes exactly…
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### Author:  [@flex727](https://boards.straightdope.com/u/flex727)
#### Post date: [April 18, 2008, 7:45pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886/14 "2008-04-18T19:45:50Z")
[QUOTE=Napier]
…Newtonian relativity…
[/QUOTE]
😕
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### Author:  [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)
#### Post date: [April 18, 2008, 7:52pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886/15 "2008-04-18T19:52:19Z")
Another recent thread on this.
[http://boards.straightdope.com/sdmb/showthread.php?t=446756&highlight=relativity+moon+landing](http://boards.straightdope.com/sdmb/showthread.php?t=446756&highlight=relativity+moon+landing)
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### Author:  [@Saint\_Cad](https://boards.straightdope.com/u/Saint_Cad)
#### Post date: [April 18, 2008, 8:05pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886/16 "2008-04-18T20:05:39Z")
But what about GPS?
Does that have anything to do with relativity?
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### Author:  [@Voyager](https://boards.straightdope.com/u/Voyager)
#### Post date: [April 18, 2008, 8:36pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886/17 "2008-04-18T20:36:17Z")
This just proves the moon landing was a hoax. They couldn’t do it since they didn’t have a GPS. So there.
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### Author:  [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)
#### Post date: [April 18, 2008, 9:16pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886/18 "2008-04-18T21:16:43Z")
[QUOTE=flex727]
> [@Napier](#):
>
> …Newtonian relativity…
😕
[/QUOTE]
See [Classical (or Newtonian) mechanics](http://en.wikipedia.org/wiki/Galilean_relativity) under Galilean invariance, also known as classical or Galilean relativity.
The GR adjustments to an Earth-Moon, or indeed a Planetary Grand Tour, are so much smaller than adjustments required due to perturbations required by planets and other errors that they don’t even figure to within the requisite significant figures. You have to do some really detailed measurements on Mercury just to see any difference from classical mechanics.
Stranger
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### Author:  [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)
#### Post date: [April 18, 2008, 9:20pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886/19 "2008-04-18T21:20:20Z")
[QUOTE=Voyager]
This just proves the moon landing was a hoax. They couldn’t do it since they didn’t have a GPS. So there.
[/QUOTE]
No, no; they had to go to the Moon in order to fake the landing because CGI technology of the time wasn’t up to snuff. The real hoax is the integrated circuit and personal desktop computers needed for modern spacecraft avionics, which are actually run by small magic sprites and fairy dust instead of “electrons” and “transistors”. Have you ever seen an electron? I didn’t think so.
Stranger
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### Author:  [@Mangetout](https://boards.straightdope.com/u/Mangetout)
#### Post date: [April 18, 2008, 9:51pm UTC](https://boards.straightdope.com/t/thoery-of-relativity-and-the-moon-landing/445886/20 "2008-04-18T21:51:33Z")
[QUOTE=MrSquishy]
Hold on a second.
I thought I heard somewhere that GPS has something to do with general and special relativity. Is that true?
[/QUOTE]
Only once, for 20 Death Rays.
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