Wednesday, March 12, 2014

Wondering about Last Night's Moon.

I went outside with the dogs the other night and looked up at the moon.  The dogs went back in and I was still out there looking up at the moon.  In my simple mind I couldn't figure out exactly why the moon looked like it did.  It looked to me like it was exactly a half moon.  Yes, I know that unless the earth eclipses the moon that the sun hits half the moon all the time just as it does the earth, but that we are not always in the right position to see it that way.


So, why would I be wondering about it?  Well, what I couldn't figure out was if the moon was exactly half illuminated by the sun, the sun had to be directly west of it, since it was the west side of the moon that was bright.  But, it was going on 23:00 and the sun had set a long time before.  Now, if you don't believe me, draw a picture.  Draw a big round circle to represent the earth, a smaller one directly above the big one to represent the moon.  Now draw a line vertically through the moon and blacken in the left half.  Then directly way off to the right of the moon, draw another circle to represent the sun.  This sketch would represent what I believed I saw last night.

Now here is the problem as I see it.  Draw a line from the center of the sun to the center of the earth.  Then draw a line perpendicular to that line through the center of the earth.  Darken in the side of the earth away from the sun.  Now, if you were at the top of the earth looking straight up at the moon so that your would see the moon half illuminated by the sun, you would be standing in the illuminated part of the earth!!  Yes, but it was eleven pm last night and it was dark. . . take my word for it, except for the moonlight.

 
The above sketch I make shows what I am talking about.  Although it isn't to scale, it does show that if I really could see a half illuminated moon, it should have been closer to sunset time then at an hour before midnight.  I must have missed something in my assumptions, because it was dark for sure.  Maybe you all can explain it to me.  Now you all go out at night and look up, you may be surprised what you see.  Mars is very bright and will get to its brightest for a while next month.  Have a great day now, you hear?

15 comments:

  1. Nope... can't explain.... but wondering how much the distance the sun is away from the earth .... and.... the orbit of the sun and moon.... have to do with where/when the light is cast? See... I told you I didn't have the answer ;-)

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  2. oops... meant earth and moons orbit

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    1. Yes, it is because the sun is just so much further away from earth than the moon is. My drawing is a little (a lot) out of scale.

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  3. I was thinking that daylight savings time might account for it, but that's only an hour we're talking about. I hope you figure it out because I doubt that I can.

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    1. No, daylight savings time had nothing to do with it.

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  4. No answer here either. I have to say though that living out here in the country we have some of the greatest star views ever. I'm amazed every time I walk out the door at night. Life is good.!

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    1. Have you noticed the fuzziest part of the sword in Orion? That is some beautiful nebulosity if you look at through a telescope.

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  5. Dang Dizzy, you took a good pic of the moon. Every time I try, everything is out of focus. Please explain your method.
    I love the moon.

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    1. Thanks BB, but I stole it off the internet. I am like you, I can never get real good pictures of the moon.

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  6. didn't I know you are/were an engineer? seems I remember that... worked for Bechtel Corporation in San Francisco in the 60s ... the engineers drove me insane! always .... dissecting ... kinda like attorneys I worked for also ... always qualifying ...

    You see the thing with us simple minded folk ... Pooh Bear types... I just look at the moon and go ahhhhhh ... especially if it's a clear black sky AND especially if it's my favorite phase.. Cheshire Cat moon.

    I also like the great big ol harvest moons...

    I see the moon, the moon sees me
    shining through the leaves of the old oak tree
    Oh, let the light that shines on me
    shine on the one I love.

    Over the mountain, over the sea,
    back where my heart is longing to be
    Oh, let the light that shines on me
    shine on the one I love.

    I hear the lark, the lark hears me
    singing from the leaves of the old oak tree
    Oh, let the lark that sings to me
    sing to the one I love,

    Over the mountains, over the sea
    back where my heart is longing to be
    Oh, let the lark that sings to me
    sing to the one I love.

    http://youtu.be/TsGcat_dJVE

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  7. I worked for myself as an designer, engineering and detailing all sorts of things from oil field, to security, to manufacturing, to just about anything you can think of. It was a lot more interesting than just going to the same job day after day after day. I enjoyed what I did for a living and I got to stay home most of the time.

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    1. Of course you enjoyed it... an engineer's mind is born ... not made ... you have lived a dream ~ very few of us can say that. certainly not I... I'm still wondering what I'll be when I grow up... options are waning... fast...

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  8. I have no much knowledge in this. Yesterday i too saw the moon. It was not half moon, it was gibbous moon. Learned some things while teaching my kid!

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    1. If I could only remember half the things I have learned over the years. . . but I don't.

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  9. "Yes, it is because the sun is just so much further away from earth than the moon is. My drawing is a little (a lot) out of scale."

    That is the answer as you well knew. The angle in your drawing would be VERY small and the lines drawn to the moon and earth would be almost on top of each other.

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