Would our moon be significantly brighter if there were few or no maria upon its surface?

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Hmmm. The albedo is not as high you may think. It is approximately equivalent to asphalt (using a loose definition of albedo). So I doubt the surface features or lack thereof would make a significant change.

it's not related with ur thread. i'm junior.......
i wanna share about the definition of creature. i don't think it needs O2 all the time. what bout nitrogen? next, d u know bout clyde?

The highlands are about twice as reflective as the maria. By eyeball, it looks like maybe a quarter of the visible disc is maria, which would give us an increment of ~15% in brightness if those areas were filled with highland material.

Grant Hutchison

So are you saying it would go from 7% to 8.05% reflectivity?

Somewhere in that region, yes, depending on what measure of albedo you use.
Which would provide a 15% increase in the amount of moonlight on a moonlit night.

Grant Hutchison

James Kaler writes in The Ever-Changing Sky that the first-quarter moon is nearly twice as bright as third-quarter because of the asymmetric distribution of maria. (I personally find this worth knowing largely because it means that if I have to do deep-sky observations at quarter moon, third is better if my targets are up that half of the night).

Third quarter is also better if you want to go to bed earlier (assuming you don't want to look at the moon!).

Nick

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We'll have to figure out what it means to be twice as bright in that sense. If you then switch the first quarter configuration into the third quarter, so that both are first quarter configurations, wouldn't that mean another third? 33% more bright? Or does the angle have something to do with it?

That's odd. Allen's Astrophysical Quantities tabulates the integral phase function for the moon at ten-degree intervals. First quarter is listed as 8.24% as bright as full moon, and third quarter is 7.80%. It highlights the strong opposition effect for the moon's surface, and shows a small difference between waxing and waning phase, but nothing as pronounced as Kaler mentions.

I wonder what's going on there?

Grant Hutchison

Such a smaller difference (more like 6%) makes intuitive sense from the covering fraction of maria. As a starting point, I just pulled up an image of the full Moon and compared eastern and western halves - the eastern (Mare Crisium) half is brighter by a whopping 2%. (Caveat - the dividing line was in equatorial rather than selenographic coordinates, which will make some difference in the maria/highlands breakdown). This isn't quite the right comparison, of course, because of illumination effects across the lit portion at quarter phases, but it says to me that the effect is a few per cent rather than a factor 2. I should have googled more deeply to begin with...

Could it be libration revealing overlapping, but different subset areas of the Moon, each with a different mean albedo?

The first quarter has few maria, while third quarter is predominently maria. Maria are darker than the foothills and mountains.

hazel, you have a question that is unrelated to the topic please take it to this part of the forum HERE

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Now I am confused about what albedo means. If we say the moon reflects 7% of the light which strikes it's surface and if the maria were gone, the result is the moon reflects 8% of the light, it is a relatively small net difference. If we add the 15% percent to the current albedo and say the reflectivity would be 22% that's huge. So huge it must be incorrect. I'm going with a net increase of 1%. Then, of the reflected light there is a 15% increase. Bottom, line, its not a big difference. It may be to a sensitive CCD or film, but not the eye.

There are several different albedos, but you've got it right, above. A 15% relative increase in reflectivity is a small absolute increase in reflectivity for an object of low albedo.
A 15% difference in luminance would be detectible to the naked eye, even in the scotopic range, if we had two uniform discs side-by-side. But it's not the sort of thing people notice without a comparison. Most people are astonished to learn that a half-phase moon is only a tenth as bright as a full moon, for instance: that's a fivefold change in luminance associated with phase angle, and we don't notice.

Grant Hutchison

I can easily tell when the Moon is full (if the sky is clear) by looking out
my north-facing windows. (Ooh-- Somebunny's been in my yard. Little
footprints in the snow!) 90% clouds, orange from streetlights, not
moonlight, but last night I could see the moonlight.

-- Jeff, in Minneapolis

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