Re: Current moon phase?

In article <11ih3isubeij99@xxxxxxxxxxxxxxxxxx>,
Dennis Allen <dennis@xxxxxxxxxxxxxxx> wrote:
> "Chris L Peterson" <clp@xxxxxxxxxxxxxxxxxx> wrote in message
> news:acrgi19u0ubn3ajvqb91ntp3rcr4vsc892@xxxxxxxxxx
>> On Wed, 14 Sep 2005 14:12:32 -0400, "Dennis Allen"
>> <dennis@xxxxxxxxxxxxxxx> wrote:
>>
>>>Hi. Last night I saw a nice first quarter moon in the sky. If you
>>>went
>>>to http://tycho.usno.navy.mil/vphase.html , however, the image is that
>>>of an almost full moon. Why such a discrepancy?
>>
>> What planet are you observing from? <g> Here on Earth, the Moon is
>> well
>> past first quarter. TheSky shows 80%, which is about what it looked
>> like
>> to me.
>
> Yes, looked like a fat first quarter but nothing close to a full moon.

This is the first time I've heard someone use the phrase "fat first
quarter moon". Normally this is called "waxing gibbous moon".

> I'm only saying that there was a noticable difference between what I
> saw and these computer images.

My guess is that this difference is because the lunar surface near the
Moon's terminator looks noticeably darker, for the obvious reason that
from there the Sun is low in the sky and therefore the ground gets
less illuminated by the Sun. And in particular if you view the Moon
through clouds or thick haze, this may make the lunar phase appear
thinner than it actually is.

The Moon remains very nearly full for a few days around full moon.
The first noticeable sign of the Moon not being quite full
anymore is one of the lunar limbs appearing noticeably darker than
the opposite limb. This happens one or two days before the shape
of the (illuminated part of the) Moon gets noticeably non-circular.

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