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Old 12-26-2008, 04:11 AM
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Can you see lit cities at night from the moon?


If you were to stand on the moon, looking towards Earth, could you see the cities on the dark side as spots of light (naked eye)? If so, what would be the ideal conditions for this?
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Old 12-26-2008, 06:31 AM
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If it's possible, I'm pretty sure it's only during a lunar eclipse, since sunlight reflected from an area in daylight or directly from the sun near the earth would outshine everything.
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Old 12-26-2008, 10:21 AM
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This is perhaps two separate questions.

First, did the Apollo astronauts see lit cities or take pictures of lit cities when they were on the moon?

That answer seems to be no. Putting earth viewed from moon into Google images beings up dozens of pictures of the earth, some of them including the dark earth. None shows any cities. Nothing that small can be seen at all.

The second implied part is whether today's much better equipment could pick up a tiny spot of light from the moon. That answer I don't know.

You say naked eye in the OP, so maybe today's equipment doesn't matter. But I believe eyes are more sensitive than the film stock used in the Apollo days so I don't want to rule it out entirely just based on the pictures.

It doesn't seem likely, though.
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Old 12-26-2008, 11:10 AM
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What's a city?

Where does Tokyo-proper end and the megalopolis start?
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Old 12-26-2008, 11:29 AM
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From the moon, with the naked eye, the Earth is about 2 across which is about twice what the Moon is to us. I would say with very good conditions, with the Earth illuminated by the Sun, continents would be visible.

From the Moon, looking at the dark side of the Earth, we have the problem that we are looking into the Sunlight so my guess is that it would not be possible to see any city lights from the Moon with the naked eye. With a telesope I am sure it must be possible though.
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Old 12-26-2008, 11:36 AM
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Since there's no atmosphere on the Moon to create haze, you could look at the Earth through a handy cardboard tube (if we could ignore the need for a pressure suit for a moment) and effectively block out any other light.

However -- consider the scale of things. We've all seen pictures of the Earth surface at night, with the coasts defined by city lights. But that's from Low Earth Orbit. If you're on the Moon, you're over a thousand times farther away.
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Old 12-27-2008, 04:15 AM
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Both the facts on my mind have been mentioned already. For one, we have all seen the pretty pictures of Earth at night from LEO. Also, we have seen the Apollo pictures with no such thing. Then again, I was guessing those pictures were exposed for the lit part to look well, not the dark part, so I don't take those to mean that it is not visible.

The city/megalopolis issue is irrelevant to this question. I don't care to discern Miami from Fort Lauderdale, I just want to see human lights from the moon.

I understand the problem of the angles involved. To see the dark part, you are either seeing it next to a lot of the bright part or the Sun, so there is always something very bright right next to it to overwhelm it. The cardboard tube idea, though, is not silly at all. The Hubble does it as do many other observatories and satellites. Masking a part of the sky to shield sensitive instruments is a reasonable way to go.

So lets' say you are looking at a well masked sky (or in an eclipse). Are man made lights too faint to be seen by the naked eye from the moon under ideal circumstances?
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Old 12-27-2008, 08:59 AM
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Originally Posted by Sapo View Post
Both the facts on my mind have been mentioned already. For one, we have all seen the pretty pictures of Earth at night from LEO. Also, we have seen the Apollo pictures with no such thing. Then again, I was guessing those pictures were exposed for the lit part to look well, not the dark part, so I don't take those to mean that it is not visible.

The city/megalopolis issue is irrelevant to this question. I don't care to discern Miami from Fort Lauderdale, I just want to see human lights from the moon.

I understand the problem of the angles involved. To see the dark part, you are either seeing it next to a lot of the bright part or the Sun, so there is always something very bright right next to it to overwhelm it. The cardboard tube idea, though, is not silly at all. The Hubble does it as do many other observatories and satellites. Masking a part of the sky to shield sensitive instruments is a reasonable way to go.

So lets' say you are looking at a well masked sky (or in an eclipse). Are man made lights too faint to be seen by the naked eye from the moon under ideal circumstances?
If your eyes are dark adapted they are pretty darn sensitive actually.

During a lunar eclipse, where virtually all the earth as seen from the moon is "dark" and the surface of the moon surrounding you is "dark" as well, my semi educated/experienced WAG is that you could see the brighter cities on earth (also assuming the sky above said cities is also fairly clear).
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Old 12-27-2008, 10:22 AM
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Originally Posted by Exapno Mapcase View Post
First, did the Apollo astronauts see lit cities or take pictures of lit cities when they were on the moon?

That answer seems to be no. Putting earth viewed from moon into Google images beings up dozens of pictures of the earth, some of them including the dark earth. None shows any cities. Nothing that small can be seen at all.
I would have thought it was more to do with inadequate exposure times than "being too small". In other words, the photos taken on the moon don't show cities for the same reason they don't show stars (conspiracy theories notwithstanding). The pictures were taken in daylight, with exposures appropriate to daylight. Maybe the astronauts saw cities, but the photos would not have shown them.
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Old 12-27-2008, 10:31 AM
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Maybe the astronauts saw cities, but the photos would not have shown them.
Which is why I explicitly didn't rule that out.

The problem remains that I don't recall any statements from the astronauts indicating that they could see cities or lights and plenty of statements that they couldn't spot any features that small. That's just my memory speaking so I'm going to hedge that as well, but I would think that any sighting of a lit city from the moon would be prominently featured in all discussions of the Apollo program.

Metropolitan areas are considerably larger and brighter today than 40 years ago so perhaps conditions have changed sufficiently to make it possible. For me the weight of the evidence still says no.
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Old 12-27-2008, 11:00 AM
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Originally Posted by Exapno Mapcase View Post
Which is why I explicitly didn't rule that out.

The problem remains that I don't recall any statements from the astronauts indicating that they could see cities or lights and plenty of statements that they couldn't spot any features that small. That's just my memory speaking so I'm going to hedge that as well, but I would think that any sighting of a lit city from the moon would be prominently featured in all discussions of the Apollo program.

Metropolitan areas are considerably larger and brighter today than 40 years ago so perhaps conditions have changed sufficiently to make it possible. For me the weight of the evidence still says no.

Small, as in angular size as seen from a distance is NOT a problem. If it is angularly small its will just look like a point source, like a star.

Brightness is the problem.

Keep in mind, you can see the light in the night sky on earth from a big city from a LONG way away.

That light is spread over a large fraction of the sky.

That light is just the light scattered by the atmosphere back towards the earthbound country dweller. Most likely significantly more continues out into space (towards the moon for example).

Sure the moon is much farther away from the city than the country dweller is. BUTTTT as seen from the moon, the light one would see would be concentrated into a near point source rather than being spread across most of the sky. My back of the envelope calculation/WAG is those two factors roughly cancel out.

My WAG is the cities would be visibly detectable, but not blaringly bright and obvious either. Which means some real calculations would be required to truelly determine the possibility of visibility.

Also remember, the astronauts were not even probably REMOTELY dark adapted. Thats the same reason they didn't report seeing many (any?) stars during their surface moon walks. Cities from earth would be on the same level of brightness as stars.

Even in their rocket/capsule on the way too/from the earth, they would not be dark adapted.

Try sitting in a brightly lit room at night. Dash outside and tell me how many stars you can see in the first few seconds or so. You will only see the very brightess ones at best..
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Old 12-27-2008, 12:49 PM
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Also remember, the astronauts were not even probably REMOTELY dark adapted. Thats the same reason they didn't report seeing many (any?) stars during their surface moon walks. Cities from earth would be on the same level of brightness as stars.
I am sure that your typical astronaut, with a job to do in a bit of a rush and totally surrounded by white floor is anything but dark adapted. You do raise an interesting point, though. Has any astronaut said whether they could see stars while on the moon? In forty years of interviews, I am sure this must have come up at some point. Specially if they went to middle schools.
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Old 12-27-2008, 06:19 PM
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Oh

Another consideration that might make it harder to see city lights from the moon is this.

During an eclipse of the sun by the moon as seen from the Earth, the "black" disk of the Earth is going to be ringed around the edge by the fairly bright atmosphere of the earth that is still in sunlight/has it passing through it.

Now, how bright it would be and whether it would be bright enough and close enough to cause problems seeing the city lights I am not terribly sure about.

thinking about it some more, I imagine it would be a not so bright very red ring.

Seeing this red ring of the earth in a jet black sky filled with many stars and perhaps a few sparkles of the larger/brighter cities would be quite spectacular IMO.

If the alignment was such that the backdrop of the eclipsed sun/earth was a brighter part of the milkyway it would really rock visually.
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Old 12-27-2008, 06:32 PM
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The "clear sky" part may be more a factor that we think. Using Google image search for "eclipsed Earth" led to some partially eclipsed Earth shots from Time, such as this one.
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Old 12-27-2008, 08:35 PM
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How bright would a 100 watt light bulb be if viewed from the distance of the moon?

This book contains a starting point:
Quote:
given that an ordinary tungsten bulb converts only about 2% of its energy into visible light, alpha centauri is as bright as a 100W light bulb shining 2.5 km away.
That may sound dim, but alphaCen is just about the brightest star in the night sky, easily visible to the naked eye.
Now, Alpha Centauri has an apparent magnitude of -.01, so a 100 watt light bulb at 2.5 km will also have a magnitude of -0.01.

The relation between magnitude and distance is taught in astronomy 101:
m - M = 5 X log (d) -5 (d in parsecs, m = apparent magnitude, M = absolute magnitude, which is the magnitude at a standard distance of 10 parsecs)
Plugging the data into this equation will supply the absolute magnitude of a 100 watt bulb, and then allow calculation of the bulb's apparent brightness at a distance of 384,400 km; the earth to moon distance.

Converting parsecs to km changes the equation to:
m - M = 5 X log (d X 3.24 X 10^-14) -5
for the light bulb:
-0.01 - M = 5 log(2.5 X 3.24 X 10^-14) -5
...
M = 70.45.

plug in M and lunar distance to get apparent magnitude:
m - 70.45 = 5 X log (384,400 X 3.24 X 10^-14) -5
...
m = 25.9

Magnitude 7 is about as dim an object as a dark adapted human can see, however, Hubble, with a magnitude limit of about 30 (see wikipedia) could see a hundred watt bulb at the distance of the moon.


Now, what about cities?
Is a city as bright as 10,000,000 hundred watt light bulbs? A gigawatt is a lot of power. Let's use that as the brightness of a point source sized city.
Magnitudes and intensity relate by the formula:
m1 - m2 = 2.5 log(I2/I1) (astron 101 again)
so we have
25.9 - m2 = 2.5 log(10000000/1)
...
m2 = 8.4

10,000,000 light bulbs of 100 watts each will only have a massed magnitude of 8.4 when viewed from the distance of the moon.
This is not bright enough for a human to see, but should be within the range of a small telescope, or even binoculars.

Last edited by Squink; 12-27-2008 at 08:37 PM. Reason: extra M =
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Old 12-27-2008, 09:02 PM
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[b]
10,000,000 light bulbs of 100 watts each will only have a massed magnitude of 8.4 when viewed from the distance of the moon.
This is not bright enough for a human to see, but should be within the range of a small telescope, or even binoculars.

to get to magnitude six or so you need another factor of 5 or so more light.

So, make it a large metro area with a larger population, make it a few hundred to a thousand watts of light per person.

Throw in a really nice, dark, and atmosphere free view from the moon and it sounds to me densely populated urban areas would just be visible faintly to a dark adapted human eye.

thanks for the calcs!
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Old 12-31-2008, 04:11 PM
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Small, as in angular size as seen from a distance is NOT a problem. If it is angularly small its will just look like a point source, like a star.
Quite so, and it gives me a chance to mention one of my favourite astronomical facts - all the naked-eye visible stars put together don't cover as much area of sky as Pluto does. (The stars are perfectly visible, despite that.)
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Old 01-01-2009, 02:53 PM
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Thanks to Squink for the the calcs. Very interesting. Do I gather from billfish678's post that there might be some visible areas as of now? 100W light bulbs inside a home are somewhat inefficient in lighting the moon, but industrial parks, highways, sports arenas and many other human enterprises are just great at polluting the sky with light.

Also, it might well be that the Earth of the Apollo era was not as bright as it is today (as someone else pointed out earlier). Maybe we weren't there yet at the time of the lunar landings but we are now.
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Old 01-01-2009, 03:32 PM
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Originally Posted by Squink View Post
10,000,000 light bulbs of 100 watts each will only have a massed magnitude of 8.4 when viewed from the distance of the moon.
This is not bright enough for a human to see, but should be within the range of a small telescope, or even binoculars.
This is also assuming no atmospheric interference of any sort.
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Old 01-01-2009, 04:08 PM
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This is also assuming no atmospheric interference of any sort.
Also no trees, buildings, or light fixtures to block off emission in the direction of the moon.
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Old 01-01-2009, 04:22 PM
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This is also assuming no atmospheric interference of any sort.
OTOH, the concept of stars' magnitude assumes atmospheric interference (twinkling).


Still, the figure for 1 lightbulb assumes looking straight at it, not its reflection off concrete or fog. That is a big distinction.

But I think we should start with what our criteria for "lit cities" is. If a city can't be more than a point source, will groups of cities also be seen as one object? Take a look at this "earth from space" map: http://indistinctunion.files.wordpre...arth-night.jpg It's a bit old ('62), but what I like is that it's not over-exposed or post-processed. If you zoom out in your browser or img program, you can get a real sense of how the cities bunch up. Western Europe, Japan-Korea-Beijing, Eastern North America, etc., bunch up into sizeable areas of light. These areas have huge populations, far more than 10 million. I think the outlines of civilization would be as visible as ridges on the moon.


Btw, anyone else find it odd that we don't know such a basic fact about our Earth? That after trillions of dollars spent on the space program, none of us, the most nerdy of the human race, knows what it looks like from space?

Last edited by Alex_Dubinsky; 01-01-2009 at 04:24 PM.
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Old 01-01-2009, 04:58 PM
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Those elves sure use a lot of lights making them toys.
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Old 01-01-2009, 08:02 PM
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Btw, anyone else find it odd that we don't know such a basic fact about our Earth? That after trillions of dollars spent on the space program, none of us, the most nerdy of the human race, knows what it looks like from space?
There are gazillions of photos of earth from space. Some of them have been taken by astronauts at various altitudes and many more have been taken from satellites at varying distances.

Just put earth from space into Google images.
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Old 01-01-2009, 09:08 PM
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Keep in mind that the Apollo landings occured during lunar morning, so that ambient sunlight would stop down their irises enough that they wouldn't be able to detect lights on the dark side of the earth. Even without that, the brightness of the illuminated limb of the earth would have the same effect. (In the famous "Earthrise" photo - I use it for wallpaper on my computer - the earth is at about 5/8 phase.)

One might be able to see lights on earth during a terrestial eclipse (or whatever they call it), but the halo effect of sunlight passing through the earth's atmosphere that someone mentioned above would probably play hob with that.


I just look at the link Exapno provided and came across this. Note the two white pixels on the dark side of the earth. Whether it's surface lighting or mere artifacts, I don't know. To judge from other photos I've looked at, probably the latter.


Well, I'm just a Googlin' fool tonight. Not sure what to make of this image. I'd bet it's a composite - check out the shadow angles on the lunar surface; the light source appears to be to the left of and slightly behind the photographer. But if the eclipse part of the photo is legit, and it seems to be, this will give you some idea of what it would look like.
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Old 01-01-2009, 09:19 PM
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There are gazillions of photos of earth from space. Some of them have been taken by astronauts at various altitudes and many more have been taken from satellites at varying distances.

Just put earth from space into Google images.
Nah, it's all retouched bs that's faker than a magazine cover.

That's the problem with NASA. It's always too self-conscious to show us things as they really are. And in the end, we don't know anything about what things really look like.
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Old 01-01-2009, 09:23 PM
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Nah, it's all retouched bs that's faker than a magazine cover.

That's the problem with NASA. It's always too self-conscious to show us things as they really are. And in the end, we don't know anything about what things really look like.
Wow. Just wow.
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Old 01-01-2009, 09:54 PM
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Well, I'm just a Googlin' fool tonight. Not sure what to make of this image. I'd bet it's a composite - check out the shadow angles on the lunar surface; the light source appears to be to the left of and slightly behind the photographer. But if the eclipse part of the photo is legit, and it seems to be, this will give you some idea of what it would look like.
While most of those pixels may once have been in an actual photo, I don't think there is anything remotely close to reality in the whole of it.

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Wow. Just wow.
Indeed.
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Old 01-01-2009, 10:05 PM
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Wow. Just wow.
What the hell are you talking about?

I mean literally what I said. Every commercial "earth at night" picture is a digital composite of an enhanced image. Every picture of a planet has been modified to add in color. Even mars is made redder than it is (as this article points out).

What the fuck are YOU getting at?
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Old 01-01-2009, 11:12 PM
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There is, of course, absolutely no doubt that the picture in BJMoose's link is a complete fake, for many reasons. First: the image of the earth is the famous Blue Marble photo taken by Apollo 17 in 1972.) Second, the image of the the moon's surface is from Apollo 15, 16, or 17 (which we know because it shows a lunar rover), and none of those missions (or any of the other Apollo missions, for that matter) was on the moon during a lunar eclipse. Finally, if any other evidence were necessary, the surface of the moon is brightly lit, which obviously wouldn't be the case during a lunar eclipse!

The Photoshop artist who created the image has assumed that the sun would illuminate a red ring all the way around the earth, similar to the one seen around the moon in a solar eclipse. But I doubt it would look anything like that. The atmosphere is only a couple of miles thick, compared to the Earth's 8,000-mile diameter. I don't think that once you, the viewer, were in the earth's shadow, you would be able to see sunlight refracted through the earth's atmosphere.

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During an eclipse of the sun by the moon as seen from the Earth, the "black" disk of the Earth is going to be ringed around the edge by the fairly bright atmosphere of the earth that is still in sunlight/has it passing through it.

Now, how bright it would be and whether it would be bright enough and close enough to cause problems seeing the city lights I am not terribly sure about.
You're a little confused. During a solar eclipse, there is no "'black' disk of the Earth." It's the disk of the moon that is casting a shadow on a small portion of the surface of the Earth.

The circumstances you describe would happen during a lunar, not a solar, eclipse. And you (like the Photoshop artist) seem to assume that a lunar eclipse as seen from the moon would appear similar to a solar eclipse as seen from the earth. But, as I said, the earth would not have the same illuminated ring that the moon displays during a solar eclipse because the earth is much bigger than the moon. It completely blots out the sun for a couple of hours, the length of the typical lunar eclipse.
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Old 01-02-2009, 05:57 AM
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national geographic recently did a piece on light pollution, by the way. it's an interresting read.
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Old 01-02-2009, 07:57 AM
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You're a little confused. During a solar eclipse, there is no "'black' disk of the Earth." It's the disk of the moon that is casting a shadow on a small portion of the surface of the Earth.

.

Not confused, just word choice challenged/dyslexic.

I've talked and written about lunar and solar eclispes hundreds of times. This is probably the first time I've talked about a solar eclispe as seen from the moon, so the old phraseology habit kicked in.

If you read for content, you can tell I was talking about seeing the sun being eclipsed by the earth as SEEN from the moon, hence the "black" disk of the "earth".

I think most of the other readers here were able to figure out what I meant
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Old 01-02-2009, 08:08 AM
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Even as bright as the U.S. East Coast, Western Europe and Japan have gotten at nighttime nowadays, I still highly doubt that you could see those lights with the naked eye from the lunar surface. Still a long way away, with the entire Earth a relatively small object in the sky.
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Old 01-02-2009, 08:54 AM
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There is, of course, absolutely no doubt that the picture in BJMoose's link is a complete fake, for many reasons. First: the image of the earth is the famous Blue Marble photo taken by Apollo 17 in 1972.) Second, the image of the the moon's surface is from Apollo 15, 16, or 17 (which we know because it shows a lunar rover), and none of those missions (or any of the other Apollo missions, for that matter) was on the moon during a lunar eclipse. Finally, if any other evidence were necessary, the surface of the moon is brightly lit, which obviously wouldn't be the case during a lunar eclipse!

The Photoshop artist who created the image has assumed that the sun would illuminate a red ring all the way around the earth, similar to the one seen around the moon in a solar eclipse. But I doubt it would look anything like that. The atmosphere is only a couple of miles thick, compared to the Earth's 8,000-mile diameter. I don't think that once you, the viewer, were in the earth's shadow, you would be able to see sunlight refracted through the earth's atmosphere.

* * *
I sure screwed the pooch on this one, didn't I? While the thing I had linked to was obviously a composite, I convinced myself that the weasel had done no more than cut and paste. Indeed, a few minutes before I had seen a thumbnail of the same "terrestial eclipse" photo (or should I say "artist's rendering"?) and that helped convince me the eclipse element was legit.

Silly me. It is indeed a diddled-with version of the Blue Marble pic. So I've made a new rule for myself: if part of a photo is obviously fake, I have no business trusting any of it.

My apologies all around.
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Old 01-02-2009, 11:09 AM
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Okay, here are some numbers as to whether you could see a red ring of the earths atmosphere as seen from the moon during an eclipse of the sun by the earth.

Two major assumptions here.

Approximately 4 vertical miles of the earths atmosphere contribute significantly to scattered light that heads towards the moon. Yes, our atmosphere is a bit taller than that. My WAG is that the very lowest part scatters absorbs TOO much light, while the upper part doesn't scatter enough. This number is probably right to within a factor or 2 or so either way.

The second assumption is that within that representative 4 mile tall/deep part of the atmosphere, 1 percent of the suns light gets scattered and makes it back out of the atmosphere. I doubt that number could be more than about 10 times higher, but it could be significantly lower (this is the part I am most unsure about).

As Squink? calculated a 100 Watt lightbulb would be magnitude 26 or so as seen from the moon.

For those that don't know, a magnitude 4 star is 2.5 times brighter than a 5th magnitude star, and a 3rd is 2.5 times brighter than a 4th and so on and so on. The brightest stars in the sky are around 0 to 1st magnitude. The faintest stars seen naked eye in a decently dark sky away from a city are about 6th magnitude. A difference of 5 magnitudes is exactly a factor of a 100. A 10 magnitude difference is 100 times a 100 and so on an so on. The Sun and full moon are large negative numbers for reference.

The amount of solar insolation is roughly 1000 watts per square meter. 1 percent of that is 10 watts per square meter, or about 1 watt per square foot of scatter light headed back into space.

Earths circumference 24,000 miles. 5000 feet per mile. 4 miles "high" of atmosphere to do the scattering. Thats 2.5 x 10^12 square feet (or watts).

Dividing by the 100 watt bulb, thats 2.5 x 10^10 times brighter than the bulb as seen from the moon. 10^10 times brighter is 25 magnitudes. 2.5 is yet another magnitude still.

So 26 magnitudes more light than the 100 watt bulb. Magnitude 26 minus 26 equals 0.

So, the amount of light from the "earth ring" as seen from the moon would have an integrated magnitude of 0, or about the amount of light from the brightest star in the sky.

Thats fairly bright. Next question is, would that amount of light spread in a thin ring of two degree diameter still be visible? My WAG is probably, but barely.

Though it wouldnt be bright enough to cause problems seeing any cities/metro areas that might or might not be visible.

Did I mess up the math any here?
  #35  
Old 01-02-2009, 12:10 PM
CC is offline
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Just saying that if the shots of earth at night that we've all seen are not time exposures, if the city lights are not enhanced in those photos, then I'd guess that from the dark side of the moon, facing the earth during a total lunar eclipse (as seen from the earth), that some large areas of city lights would be visible as specks of light. After all, in the low earth orbit shots, there are plenty of metropolim that take up a good bit of area.
  #36  
Old 01-02-2009, 03:27 PM
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Oops

I see I lost a factor of 4 (miles) there in the calcs. So the integrated magnitude is 1.5 times "higher", making it a total magnitude of -1.5 rather than zero.

Now, we need to look at the fact that the light is "spread" around the sky.

The smallest a naked eye can resolve is about 20 arc seconds (60 seconds in minute and 60 minutes in a degree). Which means even a point source like a star or an extremely narrow line won't appear any smaller than 20 arc seconds.

With the earth appearing about 2 degrees in diameter. Lets assume the ring is 20 arc seconds wide. So 2 degrees *pi* 60 *60 equals 400,000 arc seconds.

So, now what about some other objects in the sky?

M13 is a globular cluster in Hecules. It has a magnitude of 6 . It has an apparent diameter of 23 arc seconds. It is just visible to the naked eye. Take 400,000 / pi /12 /12 equals about a 1000.

So, M13 has an angular area 1000 times smaller than the "earth ring".

A factor of 1000 is 7.5 magnitudes.

Take the integrated magnitude of -1.5 and add 7.5. That equals 6. The magnitude of m13 we started with!

So, the ring has the same "area" brightness as M13. So the ring should be faintly but reliably visible in a dark sky.

Now if my 4 mile "high" atmosphere is too large or 1 percent scattering is too large then the ring might not be visible. Or change the numbers some in the other direction and it should be easily visible (but probably still not reallllllly bright).

So, like the cities themselves, this too apprears to be a borderline case that require more accurate measurements and calculations.

Uggh....I feel like the Mythbusters where they have to proclaim "possible" rather than confirmed or busted!
  #37  
Old 01-02-2009, 09:31 PM
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I don't know. When the sun shines light on the earth, which then reflects the light to the moon, which reflects the light back to the earth, it is perfectly visible.

I'll be damned if I can't see city light.

Btw, does anyone know the W/m^2 (in lightbulb equivalents) of earthlight on the surface of the new moon?
  #38  
Old 01-02-2009, 09:35 PM
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And can someone explain why the moon's surface is STILL visible during a lunar eclipse? Is it starlight? The earth's atmospheric ring of light? Or the damn cities reflecting off?

http://dsmith77.files.wordpress.com/...se-closeup.jpg

Last edited by Alex_Dubinsky; 01-02-2009 at 09:36 PM.
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