Could someone please explain my question regarding the Moon's behaviour? Thanks.

Originally posted by Ozscot
I enjoy looking at the Moon through a telescope. I know little or next to nothing about the Moon, Stars, Planets etc - but I enjoy seeing the Moon through a telescope and periodically get the telescope out on my porch to do so.

Two nights ago (10th here in Australia) I set up the telescope and there was only about 1/4 of the moon visible in a crescent shape but I watched it for an hour or so. I decided I'd do it again when there was more of the moon to see. Next night (11th) there was slightly more of the moon lit up but not enough to justify setting up the telescope. Next night (12th) there was almost one half of the Moon lit up (left side of the moon from here in Oz) and I seriously toyed with the idea of getting the telescope out but again there just wasn't enough to justify it. Later on the SAME evening I was outside again when I realised that the Moon was no longer lit up on the left hand side - it was now more the lower half which was lit up. Now this was only two or three hours after I had observed the left hand side lit up - I had no idea that the moon changes on the SAME NIGHT? Can anyone verify this for me please? I know it sounds stupid but I have never ever seen this happen before.

Thanks in advance.

Oz

Hi Oz! What you saw was natural and normal, but because you didn't set-up your 'scope (see the bold, above) you misinterpreted what you saw. You first saw a ~ straight up & down crescent, and then later saw a crescent on its side (what I call a "Cheshire Cat Moon"). You interpreted this as two different areas of the Moon lit-up. What actually happens is that, from our vantage point on Earth, the orientation of the Moon appears to change as the night progresses.

(For the next part I had to visualize things from the Southern Hemisphere, whereas I live in the Northern. I think I got it right)

When you look to the East, North is to your left, and south is to your right. If, while standing there, you were watching the Moon rise in the east, its north pole is on the left side of the orb and its south pole is to the right, from your point of view.

Several hours pass, and you go look at the Moon when it is high in the sky. Depending on where you are in Australia, the Moon might be somewhat north of the zenith. As you face north looking at it, the Moon's north pole points to your northern horizon, and is thus on the "bottom" of the orb, from your vantage point. South is at the "top".

Now go out again when the Moon is setting in the west. As you face west, south is to your left and north is to your right - the reverse of when you were facing east. By the same token, the Moon's north and south poles are reversed from what you saw at moonrise, and compared to what you saw when the Moon was high in the sky, the Moon and its half-lit side has rotated almost 90 degrees.

Go to Stellarium.org and download their excellent (and free!) planetarium software. When you set your location and the date & time, you can hit F3 and track the Moon across the sky and see what I mean.

Hope this helps.

reply to post by Saint Exupery


Thank you! Thank You! Thank You! That's precisely the calibre of reply I was hoping for! It makes sense when you explain it like that! I really can't thank you enough!

Much appreciated!

Oz

I noticed some erratic behavior here in South West Florida.

Two nights ago (4/10/11) there was a tiny sliver of crescent moon -- on the bottom.
Last night (4/11/11) the same tiny sliver grew about 50%
This afternoon (4/12/11) I saw the moon and the top of it was all visible (if you look at your fingernail as the moon, the bottom white part would be the invisible part. I was SO confused, and meant ot come on here to see if anyone else posted anything.

S&F

Originally posted by Ozscot

Originally posted by DarthPhobos
Where you eating some of those funny bun's, you know the one's with ganja in them??

Given that I'm a 51 year old father of 4 children, Author and Masters graduate (ie what would be typically defined as 'pillar of the community' stuff) I doubt that description would sit well on me.

I know what I saw - and there may well be a perfectly good scientific explanation - it's just that I haven't encountered this phenomena before. If all you have to contribute to the question is disparaging remarks re the posters character I would suggest your analytical skills would be best served on another thread - maybe one dealing with holes in the brain caused by over indulgence in mind altering substances.

Oz

Many people are seeing this and seeking answers, do a search here on ATS for "moon" and you will see what some in the northern hemisphere are seeing. There have been no answers yet and for every person who seeks them there are twelve who say it's normal or post nonsense like the previous poster.

reply to post by Saint Exupery

Or better yet instead of watching a virtual sky indoors you can go outside, look up, and decide for yourself what is normal and what isn't.

Originally posted by Ozscot
reply to post by Saint Exupery

 

Thank you! Thank You! Thank You! That's precisely the calibre of reply I was hoping for! It makes sense when you explain it like that! I really can't thank you enough!

Much appreciated!

Oz

How is that even possible?
You own a telescope so you've probably looked at the moon a few times, in fact on this occasion you looked at it several times within a short period of time. Something unusual caught your eye, something that compelled you to start a thread seeking an answer. A person basically tells you it's normal and that your eyes are deceiving you. In closing this person tells you to make stellarium your point of reference for what is and isn't happening above your head.

reply to post by Trublbrwing


Well what he says makes sense in a logical way. So tonight I will do exactly as he says and observe the light on the moon's surface as it traverses the sky at differing times. If what he says is right, then I should see the space the light occupies on the surface change as the evening wears on - if not then it's back to square one!

Oz

Actually - I've been looking around the internet obviously trying to seek an answer - Oddly enough I encountered this post from some 5 years ago on another site...

Beginning with that full moon, back in July 3, 2004, the moon would each rise with its features in the historically correct positions. (as it always had) The features would remain stationary as the moon climbed up into the sky, but then upon reaching zenith, the features would appear to suddenly rotate in the space of several hours, approx. 90 degrees! We all remember the fuss that routine caused, I am sure.

www.surfingtheapocalypse.net...

Now that guy seems to be saying the Moon itself was rotating strangely - not the light. I wasn't looking at the moon's surface per se - I was looking at the light on the Moons surface - tonight I will check both.

Oz

Originally posted by Ozscot
Thank you Illustronic, much appreciated - you just confirmed what I feared. This is Australia - where the sky last night was cloudless and brilliant. At approx 6pm I observed an almost half moon (left side) - at approx 8:30pm the angle of the lit portion had changed dramatically - on a clock face the area now lit up would be from 4 to 10.

Oz, I noticed the moon's crescent at an angle off from "left - right" a few months ago, and just stopped and studied it a minute while the core of my being said I'm wondering why it struck me as odd. Either the crescent is and has always rotated around the circle, and I failed to take in this fact as fundamental to my existence as knowing that grass is green; or the crescent has recently strayed away from looking like the iconic childhood drawing of a crescent moon.

Either scenario is disturbing, hence the

I in southeast US, by the way. My now is the way the sky looks when the sun is rising. But that's off topic. (Unless it isn't... )

reply to post by new_here


You make a good point about this. You see I saw the moon (It wouldn't really be called a crescent moon as it was 'too fat') but it was almost a half moon from the 12 o'clock position to the 6' o'clock position, but three hours later it was 10 o'clock position to 4 o'clock position - now one of the things that struck me immediately (apart from the fact that it had moved) - was that I don't think I had ever seen that shape on the moon before - but because I have only been in Australia for 5 years I presumed there was something about observing it from here that I didn't understand.

Oz

reply to post by Saint Exupery


Sounds kinda like your describing a crescent moon tilt hard to tell without pictures. This happens at certain latitudes its caused by the earths tilt of 23.5 degrees.And yes this effect can change rapidly. What it amounts to is a crescent moon which normally looks like a c looks more like a u with the bottom of the moon showing. google it for an explanation but it has been known to occur for centuries i remember the first time i saw it kinda freaked me out.

Originally posted by ThaLoccster
I've been watching the moon with my telescope every night since the 6th and I haven't seen anything like that. I actually like to look at the moon when it's partially lit or otherwise not full, it does get real bright the fuller it becomes I'm usually up til early in the a.m. and I walk my dogs frequently throughout the night, I always take time to observe the moon and the sky.

I haven't seen anything remotely resembling what you have described over the past week.

Well i have seen the moon do that here.

Originally posted by Ozscot
reply to post by new_here

 

You make a good point about this. You see I saw the moon (It wouldn't really be called a crescent moon as it was 'too fat') but it was almost a half moon from the 12 o'clock position to the 6' o'clock position, but three hours later it was 10 o'clock position to 4 o'clock position - now one of the things that struck me immediately (apart from the fact that it had moved) - was that I don't think I had ever seen that shape on the moon before - but because I have only been in Australia for 5 years I presumed there was something about observing it from here that I didn't understand.

Oz

I think 5 years is plenty of time to notice a shattered fundamental truth you've held for 45 years. You seem bright enough to spot something of that magnitude on first glance. Like if you looked out your window and your grass was orange... LoL

reply to post by Trublbrwing


yes I agree and today and through the night I shall photograph the moon every hour and will post them here... I am so frustrated with people telling me its normal. Im a 39 year old man who has always watched the moon and stars. Im pretty sure I know what is normal moon behaviour and what is not. and I just cant get my head around this, How the moons shadow can be vertical at four in the afternoon, then rotate to the right and be horizontal at about nine pm, and then again at about one in the morning be almost vertical again. It has been exactly the same since November. Every day, every week, and it is not normal. I live in Grenwich, London, weather permiting I shall post pictures later.

Well, it's now 4:15pm here in Qld. The Moon is already high although it's bright daylight and bright sunshine. It's a half moon but with the area from 8 o'clock to 2 o'clock floodlit. I'll check it out again later.

Oz

I couple of things I need to clearify from my previous post (My apologies; I was in a hurry):

First, I mentioned that he should have looked at the Moon through his telescope. This so that he could see for himself that the direction of the illumination in relation to the Moon had not changed. In other words, it wasn't that the eastern half of the Moon was lit, then later the southern half. Rather, it was the same part of the moon was lit, but the Moon's north-south orientation to the horizon had changed.

Secondly, I recommended Stellarium for the simple reason that you can speed-up the simulation and view in a few seconds what would otherwise take many hours to observe.

Unless someone out there knows how to speed-up celestial mechanics...?

(Edited to add) One more thing: if you watch the constellations, such as the Southern Cross or (in the north) the Big Dipper, you will see the same rotation of orientation that the Moon does as the night progresses.

Saint Exupery - I have indeed observed the Southern Cross and of course other stars weave their way across the sky and reorientate themselves at night. Tonight the Moon is doing precisely as it did last night - it is now being illuminated in a differing section from that a few hours ago - now it's 4 o'clock to 10 o'clock which is illuminated. So yes there is a steady progression of shifting light across the moon as the evening wears on - but I had no idea that this was 'normal' - of course it makes me sound pretty stupid that I was unaware of this. But it is clear from some of the disparaging comments in this thread that there were others who thought I had made this up - so quite clearly they are in the same stupid basket as me as they were unaware that this is in fact how the Moon progresses through an evening lol.

In all my life I had no idea that this progression takes place - I obviously haven't been paying enough attention on any given night. So just to confirm - what I am witnessing is perfectly normal...Yes?

Oz

reply to post by Ozscot


Yes. However it occured to me that in your case, there may have been something else at play. I read in this post that you have been living in Australia for only 5 years. If I may be so bold as to guess, may I assume from your nickname, "Ozscot" that you moved there from Scotland?

The lit side of the moon is always in the direction of the sun.
Because the sun is what lights it.

For a half moon...
Just on sunset, the lit part will be on the side, because the sun is at the horizon, in a direction you see as sideways from the moon.
At midnight, the lit part will be the bottom, because the sun is below your feet.

Note that the *actual lit part of the moon does not change*.
That it looks like this is all your fault really.
You, the observer, are not still, and are rotating on a planet while trying to look at objects in space. The rotation of earth causes you to have a different perspective on the same objects in space (sun, moon) from one hour to the next.

Go outside one day, midday, with a basketball. The lit part is on top, nearer your head.
Now balance upside down on your head. From your new perspective, the lit part is the area closest to your feet.
Now lie on your right side. The lit part of the ball is closest to your left side.
The rotation of the earth, and you with it, causes the same change of perspective when looking at the moon.

The sun and moon dont care, they remain the same.

reply to post by Saint Exupery


LOL Good deduction I am indeed from Scotland.

Oz