[ngcles]

Hi Dave,

Originally Posted by AstralTraveller

Well he did go on to say ".....but anything that gets people outside looking at the sky is a good thing." and so redeemed himself.

On that reasoning the "Mars-Hoax" email that goes around every year regarding August 28th and Mars looking as big as the Full Moon, would also be a "good thing" because "anything that gets people outside looking at the sky is a good thing".

Sorry, I can't subscribe to that species of reasoning. For mine it goes in the same bucket as "Never let the facts get in the way of a good story ..."

Originally Posted by AstralTraveller

BTW an old song just popped into my head (nature abhors a vacuum ) singing "by the light of a silvery moon". I've always thought of the moon as white (or very bright gray) and lacking a metallic sheen. Can you tell me why the moon would appear silvery and how often this happens?????

I dunno the answer to this off the top of my head -- so I'll have so see if I can find a proper answer from somebody who knows better than I.

The Moon has a very low albedo and only reflects about 7% of the light hitting it. This is about the same reflectivity as newly-laid bitumen. So why doesn't it look completely black?

My guess (without having a proper answer at the moment) is that it is a function of having a very dark sky to view it in (at night anyway) and its size. The Moon doesn't look bright in the day becasue the surface-brightness of the sky virtually matches it.

The reflectivity of the Moon also varies from phase to phase depending on how much of the darker maria are on view and how much of the brighter highlands are on view. Another factor is that near Full Moon there are few if any shadows and we "face the Moon squarely" -- so to speak, so it has a higher surface-brightness per unit of illuminated area and the Sun is shining directly down on the Moon rather than being an oblique angle of illumination.

Silvery -- yep it does look kinda-that way to me naked eye but more like alabaster through the telescope I'd reckon. In fact I've just finished taking a look at it through the telescope in the backyard and my wife thought it looked like plaster of paris.

But in the end, my guess is that "silvery" is in the lyric because they needed a three syllable word that fitted the meter of the lyric and beat. "white-y" or "alabaster-y just doesn't cut the mustard!

Yes, I look at the Moon through a Telescope! (Gasp!!) Almost unbelievably, my wife looked tonight too. (Double Gasp!!)

I took a look tonight in particular because I wanted to check everything with the ArgoNavis/Servocat was okay (the Argo just had a service call) and I was interested to see Schroter's Valley -- and the angle of illumination on that part of the Moon just happened to be right. Looked very nice at x371 !!

http://the-moon.wikispaces.com/Schroter's+Valley

One of the most interesting bits on the Moon I think.

The seeing tonight is also quite good -- could split Sirius (ie see the "pup") at x317 with little difficulty. And I also wanted to see a couple of O.C's I'm researching too.


Best,

Les D