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Author Topic: How can the moon's position look strangely tilted sometimes?  (Read 19151 times)

Offline Traianim

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Hi,

Last night, my girlfriend and I have witnessed a very strange moon position. It was unlike the "text book" pictures we have gotten used to.
The moon was tilted as a "smiley face" which we found very unusual. From my point of view, the moon should never be in such a position because it does not support the lunar phases.

I have looked up on the Internet the subject and all sorts of weird conspiracy and doomsday theories came up. Amazingly, these websites had pictures and videos of the moon identical to what we had witnessed last night, but there was no hard scientific explanation behind the phenomenon.

Can anyone help explain how come the moon can appear tilted in such a way ("smiley face")?

Thanks a lot,
Traianim


 

Offline Pikaia

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How can the moon's position look strangely tilted sometimes?
« Reply #1 on: 07/02/2011 13:49:41 »
The appearance of the moon was perfectly normal.

First of all, the Moon was 3 days old, which means it is roughly where the Sun will be in about five weeks, ie much further north. On top of this, the moon's orbit is tilted relative to Earth's, and because of this the moon was even further north of the Sun.

So the moon would have been almost directly above the moon from mid-northern latitudes, and the illuminated part would have been at the bottom.

If you think of the crescent moon as a bow, then an arrow fired from it would travel straight towards the sun, and this is what you would have seen.
 

Offline waytogo

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Hi,

Last night, my girlfriend and I have witnessed a very strange moon position. It was unlike the "text book" pictures we have gotten used to.
The moon was tilted as a "smiley face" which we found very unusual. From my point of view, the moon should never be in such a position because it does not support the lunar phases.


Hi there, I agree with you, I'm pretty sure that something it's going on with the moon, but not necessarily doom.

I've notided that since late 2007. The moon on our northern latitude (center Europe), started to spin a bit. Someone did say that it was because of moon's libration, but now it rotates even with lots of degrees and then they changed their minds thinking that's because of field rotation (ridiculous) as it happens when you see the stars rotating in the sky during hours.

Yestarday for example, I saw the waning "gibbous" moon rising with its shadow tilted up to 45 degrees.

The moon is not acting as it shoud be (standing vertical even on phases).
« Last Edit: 12/09/2012 09:25:03 by waytogo »
 

Offline waytogo

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This is how the moon looked like yestarday on the rising (@ northern hemisphere) so that configuration was visible to all Europe / USA.

http://i1249.photobucket.com/albums/hh508/myfreepbaccount/TheMoon/d78eb5a0.jpg

Any clues?
« Last Edit: 12/09/2012 09:39:09 by waytogo »
 

Offline Orbit

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just by looking at the side of the moon that is lit, you can work out where the sun must be for its light to shine there and not the dark side.

From just deducing where the sun is relative to the moon you can work out how you must be from where you are on Earth. ( i.e. your latitude and longitude greatly matter)
 

Offline waytogo

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Anyone got a clue?
 

Offline Ophiolite

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There is nothing unusual here, unless you consider the late development of observational skills to be unusual.

1. There are enough amateur astronomers observing the moon on a daily basis that anything remotely out of the ordinary would be spotted at once.
2. Nothing at all has been reported.
3. Your descriptions of what you are seeing are phrased ambiguously, which makes providing a clear explanation for your misinterpretation difficult.
4. Misinterpreting is exactly what you are doing. You are noticing something commonplace for the first time.
5. In summary, nothing to see here; move along.
 

Offline wolfekeeper

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I think he's talking about seeing the phase of the moon not appearing to line up with where the sun is.

I've seen this myself. It was quite disconcerting. The crescent was tilted with where the sun was.

It's actually a reasonably well known optical illusion though; the phase of the moon is always lined up with the sun, for obvious reasons, it just doesn't look like it.
 

Offline Ophiolite

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Interesting. I have never noticed that before. What do you understand to be the underlying cause of the illusion.
 

Offline wolfekeeper

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Dunno, but it's difficult to measure angles when they're 90 degrees apart in the sky and you have to turn your head to see each.
 

Offline waytogo

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There is nothing unusual here, unless you consider the late development of observational skills to be unusual.

1. There are enough amateur astronomers observing the moon on a daily basis that anything remotely out of the ordinary would be spotted at once.
2. Nothing at all has been reported.
3. Your descriptions of what you are seeing are phrased ambiguously, which makes providing a clear explanation for your misinterpretation difficult.
4. Misinterpreting is exactly what you are doing. You are noticing something commonplace for the first time.
5. In summary, nothing to see here; move along.

Well, now you should demonstrate it. So why the moon is acting like that? Obviously you can use formulas to support your beliefs if you want.
« Last Edit: 24/09/2012 16:01:00 by waytogo »
 

Offline Ophiolite

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That is not how science works. You are asserting that there is something unusual going on. The responsibility to demonstrate that lies with you. Without a clear demonstration all we have is some confused eye witness reports. You are of course free to continue to believe you have spotted something remarkable. If you wish others to believe you then you will need to produce evidence.

This may seem harsh and negative. It is intended in the reverse. Since I know there are oodles of amateur astronomers out there with an interest in the moon I am confident anything unsual would already have been spotted. There are no such reports. Therefore you are, in some manner mistaking what you see. It would be irresponsible and arguably rather nasty to let you continue with a false belief.
 

Offline waytogo

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@Ophiolite

So, for you it's normal to see the moon tilting up to 90°?  tell me.
 

Offline Ophiolite

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1. It depends where I am on the planet.
2. You have not demonstrated that it was tilted to 90 degrees.
3. Since I don't trust my own eye witness testimony why would I trust yours?
 

Offline waytogo

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1. It depends where I am on the planet.

No, it does not, even if you stay near the equator all the night long.
(obviously before that phenomena we are talking about started, maybe now it rotates more than usual).

Any Australian or Mexican Here?

2. You have not demonstrated that it was tilted to 90 degrees.

It does.

3. Since I don't trust my own eye witness testimony why would I trust yours?

Oh, well. I guess that expalin something.
« Last Edit: 24/09/2012 22:08:08 by waytogo »
 

Offline CliffordK

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I suppose I have not spent enough time gazing at the moon.

The Earth's axis of rotation tilts at about 23.4°, causing the appearance of the sun to move North and South with the seasons. 

The moon also has a tilt of about 5.14° from the ecliptic (in relation to the sun).

Different angles of the moon would be related to the relation of the orbital tilt to the eclipse, and whether you are looking at it just prior to, or just after the new moon.  It would also be related to where the sun is rising and setting with respect to the seasons, and where a person is on Earth, and thus the viewing angle.

With careful observations, I would not expect a person to see huge day to day changes.
 

Offline wolfekeeper

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Interesting. I have never noticed that before. What do you understand to be the underlying cause of the illusion.
I was just looking at the moon today. It was almost exactly sunset, and the crescent of the moon was to the South and seemed to point slightly upwards. If I looked at the moon, and then turned my head towards the sun, it looked like the moon was pointing significantly upwards with respect to the sun.

But it's obviously an illiusion.
 

Offline Ophiolite

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No, it does not, even if you stay near the equator all the night long. Any Australian or Mexican Here?
Then you need to define more clearly what the 90 degree angle is between. For sure the angle varies relative to the horizon (and in other ways, as noted by CliffordK).

I've looked at the moon from Australia and from Mexico, from southern Africa and inside the Arctic circle, and many points in between. It varies.

2. You have not demonstrated that it was tilted to 90 degrees.
It does.
And if you told me it was towed through the sky by green unicorns ridden by invisible cherubs I should automatically accept this.

You still have not explained how many hundreds, or more, amateur astronomers have not noticed the supposed change. Will you do so now? While you are at it will you explain the following. Every day a laser is fired at one of the reflectors left by Apollo astronauts on the surface of the moon and the time for the beam to come back to the Earth. If the moon had moved in some strange way then that reflection could not occur. Please explain that.

3. Since I don't trust my own eye witness testimony why would I trust yours?
Oh, well. I guess that expalin something.
Eye witness testimony is notoriously unreliable. It is generally disregarded in science, which is why observations typically have to be repeated many times, preferably by different researchers before data are accepted. There is no reason you should have known this, but now that you are aware of it I hope you will rethink your position.
 

Offline Astromut

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Well, now you should demonstrate it. So why the moon is acting like that? Obviously you can use formulas to support your beliefs if you want.
Ok.  It's dependent on field rotation as well as where the moon is in relation to the sun in the sky.  It's completely normal and can be proven mathematically.
newbielink:http://www.youtube.com/watch?v=R4eDT8-73ZE [nonactive]
All the formulas are right here:
newbielink:http://dropcanvas.com/edwxo [nonactive]
 

Offline waytogo

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Ok.  It's dependent on field rotation as well as where the moon is in relation to the sun in the

Sorry, not moon field rotation  here, I really dont know in whitch book did you find that, the moon normally does not rotate at all several degrees in just some hours in normal condition from the Earth view (you may confused it with the libration, but that one is very slow and the tilt is no more than in about 6 degrees only). No offense, but you may study basic astronomy in good ones.
 

Offline Astromut

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Ok.  It's dependent on field rotation as well as where the moon is in relation to the sun in the

Sorry, not moon field rotation  here, I really dont know in whitch book did you find that, the moon normally does not rotate at all several degrees in just some hours in normal condition from the Earth view (you may confused it with the libration, but that one is very slow and the tilt is no more than in about 6 degrees only). No offense, but you may study basic astronomy in good ones.
I specifically mentioned the book used at the beginning of the above video.  Lunar tables and programs from 4000 B.C. to A.D. 8000 by Michelle Chapront-Touzé and Jean Chapront.  From that you can calculate the apparent geocentric coordinates of the moon.  The next step is to calculate for geocentric parallax and the figure of the earth to produce topocentric coordinates specific to a given location on earth's surface.  Then you need to also calculate the phase angle and the position-angle of the phase angle (naturally this will require you to also calculate the position of the sun, but for the purpose of calculating the appearance of the lunar phase you can do so using a simple formula for the equation of the centre, true anomaly = mean anomaly + 360/pi * eccentricity * sin(mean anomaly) ).  With these figures in hand all you have to do is then convert from equatorial coordinates of the moon to altitude-azimuth.  If you also do this for the equatorial north point of the moon (same coordinates as the center point but with declination + .25 degrees) you will be able to calculate the apparent orientation of the moon due to field rotation and add in the position-angle of the moon's phase to find the apparent orientation of the moon's phase relative to the horizon. 

You can find the formulae needed to perform all these calculations in a number of books, including "Practical Astronomy With Your Calculator" by Peter Duffett-Smith and "Astronomical Algorithms" by Jean Meeus.  The end result of doing these calculations is that you can see that the apparent orientation of the moon DOES change by many degrees from rising to setting, up to 180 degrees. 

You wanted to know why the moon does that with formulas to support the explanation, there it is.  The formulas for the moon's appearance are all right there in the excel sheet I posted:
newbielink:http://dropcanvas.com/edwxo [nonactive]
« Last Edit: 12/04/2013 03:29:10 by Astromut »
 

Offline yor_on

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Impressive Astro :)
4000 BC to 8000 AD..
 

Offline Astromut

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Thank you!  I should point out that the prolonged time period for which the spreadsheet is accurate only applies to the position of the moon.  I used a simplified method to calculate the position of the sun relative to the moon in order to calculate the phase angle and orientation, and though it is sufficiently accurate for the modern era, it will not hold that accuracy for thousands of years into the future or past.  I'm working on expanding this sheet's functionality to include the planets and increase the accuracy of the sun's calculation as well, though again my main interest is in getting accurate modern values rather than accuracy over millennia.
 

Offline waytogo

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you can see that the apparent orientation of the moon DOES change by many degrees from rising to setting, up to 180 degrees. 



Again, the moon normally does not rotates several degrees from the earth view per hour, you may study a little bit more.

And thats the basics.
« Last Edit: 17/04/2013 10:38:21 by waytogo »
 

Offline Astromut

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you can see that the apparent orientation of the moon DOES change by many degrees from rising to setting, up to 180 degrees. 



Again, the moon normally does not rotates several degrees from the earth view per hour, you may study a little bit more.

And thats the basics.
Then show where my calculations are wrong, because my calculations do show that it is normal to see it rotate several degrees per hour.  I have given you multiple references which back this up.  Show where they're wrong.  You previously said "obviously you can use formulas to support your beliefs if you want."  Well I have given you all the formulas needed to see that this is normal.  They're in my excel sheet and they're in the books I referenced.  You can't just assume that they're wrong, it's up to you to prove that they're wrong.
 

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