Giant Moon

  • Thread starter Bladibla
  • Start date
343
1
Couple of months ago there was a thread on Orange moons (but not bears), with this website showing a ..giant moon.

Does anyone know where in the world i can see such large moons?
 

Evo

Mentor
22,867
2,343
My daughter and I saw one like that before. We were driving on a hill leaving her friend's house. I have never seen the moon quite that big since, I guess all conditions were just right. There are a couple of variables, the distance above the horizon and also the angle from which you are viewing. For example, when I start to go up the hill near my house, the moon looks very large but it appears to get smaller as I near the top of the hill. The full moon during certain times of year is directly ahead on this road.
 

BobG

Science Advisor
Homework Helper
110
80
You can see the Moon from most places on Earth.

The Moon appears biggest when it's low in the sky. The Moon is inclined 5 degrees from the Earth's orbit around the Sun, not the Earth's equator. That means the Moon doesn't appear to follow the same path across the sky when we look at it. It's lower in the sky in the Fall.

The Moon looks especially big when the Moon is full and the Moon is at its closest point to the Earth (the Moon's orbit around the Earth is elliptical). The next time this happens is June 22 & 23 (June 22 is the full moon and June 23 it the Moon's closest approach this month).

The full moon and perigee occur on the same day in August and are only about a day and a half apart in September, so both should look pretty big, it being closer to Fall. (The full Moon is usually pretty close to perigee every Fall, hence the Harvest Moon reference - the full Moon is usually pretty close to apogee every Spring, which is why you don't hear much about the Spring Moon).

Edit: Actually, when I think about, I think that website gave the wrong reason for the Moon appearing bigger. A full Moon should appear lower to the Northern hemisphere in the Summer, since the Moon will actually be in the Southern Hemisphere at the time of the full Moon. A full Moon should appear lower to folks in the Southern Hemisphere in their Summer.

I think the main reason is having a full Moon at perigee, plus having the right atmospheric conditions.
 
Last edited:

Monique

Staff Emeritus
Science Advisor
Gold Member
4,104
63
I once saw a giant moon that was hanging just above the horizon straight down the road; I thought the world was coming to an end, but my dad didn't seem too concerned :tongue: It's a magic sight!
 

matthyaouw

Gold Member
1,137
4
I'd heard that the moon appearing large when low in the sky was an optical illusion. It appears larger when you compare it to objects on the horizon than when it is high up.
 

Astronuc

Staff Emeritus
Science Advisor
18,553
1,682
The moon's orbit is not that irregular (i.e. elliptical) so it occupies roughly the same area or solid angle when observed from the earth's surface. It appears larger only because one has a reference near the horizon.
 

DaveC426913

Gold Member
18,233
1,837
Yes, the "large Moon" is a myth. The Moon's size does not change appreciably at any time (though it does change a small amount due to its elliptical orbit, you'd have to be pretty perceptive to notice). The large moon is indeed an optical delusion, caused by the brain's interpretation of objects when it has a reference to compare them to - such as objects on the horizon. This illusion will not fool a camera, which will record the Moon at the same size.


BTW, the giant Moon seen in that picture at the link the OP posted (assuming it isn't just two pics superimposed) is created using a telephoto lens. Take a picture of the Moon rising over a hilltop from very far away, and use a zoom lens to get close. The net effect is that the Moon looks giant compared to the foreground objects. You can do this with any two objects separated by a great distance.


Note: Although both the above "giant Moon" effects are acheived by comparing the Moon to forground obejcts, the two effects are *completely* unrelated to each other.

One is a brain thing (and thus an illusion) and the other is a mechanical-optical thing (not an illusion, but a carefully constructed scene).
 

Evo

Mentor
22,867
2,343
DaveC426913 said:
Yes, the "large Moon" is a myth. The Moon's size does not change appreciably at any time (though it does change a small amount due to its elliptical orbit, you'd have to be pretty perceptive to notice). The large moon is indeed an optical delusion, caused by the brain's interpretation of objects when it has a reference to compare them to - such as objects on the horizon.
That's the common explanation called the Ponzo effect or illusion.

But I disagree that it can explain the HUGE moon phenomena. I have witnessed the HUGE (not just larger on the horizon) moon phenomena.

The moon can appear unusually large without any objects being visible to compare it with. The time my daughter and I saw that HUGE moon, there was nothing but clear land as far as the eye can see. It's something you won't understand until you see one for yourself. No, the moon doesn't get physically larger, it's a special set of conditions that makes it appear larger, like a huge magnifying lens. In this instance, the moon does actually occupy more space in your "sight", contrary to what I've read that says if you measured it, it would be the same size as a normal size moon. I rounded a corner and was shocked, the moon was covering half of the horizon, it covered most of my rear view window. It startled me so much I gasped and scared my daughter, who then turned around and saw it. I slowed down to almost a complete stop it was so incredible.

The special atmospheric conditions must create some type of phenomena that simulates looking through a magnifying glass. If you were to measure a fly that was magnified ten times, the "magnified" fly you are seeing does actually measure larger than the real unmagnified fly. It has nothing to do with comparing other objects to it. I am quite sure the phenomena could be photographed because it is atmospheric and not something created in the brain. This isn't the "Ponzo effect", which is the normal moon on the horizon optical illusion, this is something entirely different.
 

mahoneko

I think only EVO understands the real giant moon phenomena. It is real.

I remember about 7 years ago turinging down a road with a flatish horizon stetching out ahead of me. It had been a hot day in the summer and it was early evening. A nearly crashed the car:bugeye: when I saw the moon ahead of me, only the top half was visable over the horizon but the moon filled my entire visual field - this was no optical illusion (in the perceptual sense), I am sure it must be due to some kind of lensing effect, like a mirage due to the heat of the day. It really looked like it was about to crash into the earth, you could seee enormous detail, it was a very sharp image. It might have been orange color, I'm not sure. I am amazed that I cannot find a photo similar to what I saw - shame this was all before we had digital cameras on our mobiles!

I saw this near Oxford in the UK.
Chris Bartlett
 

brewnog

Science Advisor
Gold Member
2,701
7
I've seen it two, I was driving home one summer evening about three years ago, I also almost crashed the car! It appeared to be around twice the size of a 'normal' moon, and had a really orange glow to it, although the sky around it appeared the normal pale blue you'd expect of a summer evening.
 
1,120
7
I didn't come close to crashing the car, but a giant moon rising over Dead Horse, Nevada, was really something special.
I think I'll take my dog out tonight and teach her how to howl at the moon :smile:
 

Ivan Seeking

Staff Emeritus
Science Advisor
Gold Member
7,093
174
Bladibla said:
Does anyone know where in the world i can see such large moons?
http://img77.echo.cx/img77/6865/redneckparty0vj.jpg[/QUOTE]
 
343
1
Ivan Seeking said:
http://img77.echo.cx/img77/6865/redneckparty0vj.jpg
[/QUOTE]

You just mentally scarred me for life... :yuck:
 
639
2
the moon looks really huge here right now. i've been admiring it all week. its so big and orange, its amazing. everytime i drive at night i stare at it. its really neat.
 
343
1
Gale17 said:
the moon looks really huge here right now. i've been admiring it all week. its so big and orange, its amazing. everytime i drive at night i stare at it. its really neat.
Could you maybe get a photo for us? :!!)
 

Evo

Mentor
22,867
2,343
Ivan Seeking said:
Tonight and tomorrow night will be the best.
http://www.timesonline.co.uk/article/0,,2-1663827,00.html

Everyone here at PF should go out and howl at the moon at midnight.
Well, okay, Danger can anyway.
From my window I can see the moon and it's abnormaly large and it's orange. Very cool.

That's not what I'm talking about.

I'm talking about once in a lifetime, moon the size of half of the horizon, have you EVER seen the moon that big? This isn't the normal "ooh the moon looks really big tonight" optical illusion. This is OMG, That's not possible!!! big. Like the moon has left it's orbit and is crashing into the earth big. It's got to be some freak atmospheric condition that is extremely rare and causes some type of magnifying effect. I've seen the moon twice it's normal size quite often. This is NOT what I'm talking about! Sounds like Mohoneko might have seen one of the freak HUGE moons.
 

mahoneko

Right now, the moon is particular big as it close to the earth, but the moon I saw was not twice as big, it covered my whole field of vision in one direction - it was 20+ times bigger - probably a mirage effect.

I think we are all getting confused between two different phenomena here.
 

brewnog

Science Advisor
Gold Member
2,701
7
mahoneko said:
Right now, the moon is particular big as it close to the earth, but the moon I saw was not twice as big, it covered my whole field of vision in one direction - it was 20+ times bigger - probably a mirage effect.

I think we are all getting confused between two different phenomena here.
Ok, no. I've never seen anything nearly that big! But it sounds pretty special.
 

Related Threads for: Giant Moon

  • Posted
Replies
1
Views
709
  • Posted
2
Replies
25
Views
3K
  • Posted
Replies
5
Views
3K
  • Posted
Replies
3
Views
4K
Replies
5
Views
4K
  • Posted
Replies
19
Views
6K
Replies
5
Views
2K
Replies
40
Views
2K

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving

Hot Threads

Top