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Thread: Question about views of the moon...HELP?

  1. #1 Question about views of the moon...HELP? 
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    Hi Guys and Girls,I am a newbie and a bit stuck on a question about a view of the moon.If I post a screen shot of the question could someone here help as I a confused about the correct view....Thank you in advance.


    Last edited by Daveeeboy; May 25th, 2013 at 01:09 PM.
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    Please see attached the paper with the question highlighted in yellow and the answer highlighted in pink. Please could someone check that the answer is correct and explain how it is correct if so?
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  4. #3  
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    Perhaps this can help you sort out your question:
    Moon Phases / Lunar Phases Explained
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    The only problem with the diagram in the above link is that, even though it denotes the Sun to be on the right and the inner moon diagrams are correct, with the outside pictures of the moons phases the bottom diagrams are reversed, showing the moon to be lit from the left instead! Look at the third quarter moon and the direction of the sun! After 14 days, the Sun isn't on the opposite side of the sky - that takes 6 months! This is why someone answering that question might pick the 1 mark answer rather than the 2 mark answer.

    Try this:
    "Ok, brain let's get things straight. You don't like me, and I don't like you, so let's do this so I can go back to killing you with beer." - Homer
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    Quote Originally Posted by Neverfly View Post
    Perhaps this can help you sort out your question:
    Moon Phases / Lunar Phases Explained
    Thank you for the link but I still can't find the answer.....
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    Thank you SpeedFreek for your reply,

    I think I understand it now...

    This is how I am think of it:

    365 days (a year) / (divided) by 14 days
    = 26 days

    There are 4 days between each phase so 26 / 4 = 6 moons.

    Counting the moons from the one in part i (the waning crescent) in an anticlockwise direction 6 times you get to the waning Gibbous. Which is the answer stated in the mark scheme.
    However surely there is an easier/quicker way to work this out?

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  8. #7  
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    Quote Originally Posted by Daveeeboy View Post
    Thank you SpeedFreek for your reply,

    I think I understand it now...

    This is how I am think of it:

    365 days (a year) / (divided) by 14 days
    = 26 days

    There are 4 days between each phase so 26 / 4 = 6 moons.

    Counting the moons from the one in part i (the waning crescent) in an anticlockwise direction 6 times you get to the waning Gibbous. Which is the answer stated in the mark scheme.
    No sorry, the answer is not waning gibbous. The moon isn't three quarters of the way around its orbit 14 days later, it is only halfway round.

    14 days after a waning crescent, you have a waxing gibbous, as shown in your diagram.

    A waxing gibbous as generally depicted when showing the phases of the moon looks like the 1 mark answer.

    Actually, the more I look at this and try to find a way to explain it, the more I think the 2 mark answer is wrong! The moon and sun always both rise in the east and set in the west. But 14 days later, the moon is on the opposite side of the Earth, so you would see it at the opposite end of the day.

    So, if the moon were up during the day in the first case, the moon would be up during the night 14 days later. In which case the sun would be on the other side of the moon, from the view of the student sitting on the Earth, 14 days later.

    This makes my head hurt!
    "Ok, brain let's get things straight. You don't like me, and I don't like you, so let's do this so I can go back to killing you with beer." - Homer
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    Question:Moon3.jpg
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    Answer:moon2.jpg
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  11. #10  
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    If the above answer is correct, please could someone explain in simple terms how?
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  12. #11  
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    Anyone? Nudge nudge
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    There doesn't seem to be anyone else around at the moment, but I have been thinking about this for a while, and whilst I first thought I understood the 2 mark answer, it seems I hadn't understood it at all. But since then, it hit me.

    It depends where you live, because the moon's orbit is inclined in relation to the rotation of the Earth.

    Way up here in the Northern Hemisphere, it doesn't matter where the moon is in its orbit, we always view it in a southerly direction, although sometimes it is very high in the sky. So in our case, the 1 mark answer is correct. Deep in the southern hemisphere, they would always view the moon to be in a northerly direction. Again, the 1 mark answer would be the correct option out of the choices available.

    But for someone near the equator, the moon is northerly for one part of the month whilst it passes overhead and then is southerly for the other part of the month, so unless you want to bend over backwards to look at it you have to turn round once it has passed overhead! The moon will now be the other way up, and what was the left side will now be the right side. Now the 2 mark answer is correct. But I'm not sure I believe this was the intention of the paper. I mean, the moon doesn't actually flip or anything, and nor does a person near the equator actually face the opposite direction 14 days later, they just face a varying degree south of the equator on average for part of the month and north of the equator for the other half. In their view the moon goes from being one side of sideways to the other side of sideways!

    If that was the intention of the question, I am wondering at what level these questions are aimed, and where you live? If the questions were for people who live in equatorial regions, they might be getting extra marks for knowing not only the phases of the moon (1 mark answer) but that the moon is northerly for part of the month and southerly for the other. Seems kinda harsh to everyone who put the 1 mark answer though.

    I still think this is tenuous, to say the least. The 2 mark answer might just be wrong, or misleading.
    Last edited by SpeedFreek; May 26th, 2013 at 07:54 PM.
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  14. #13  
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    Quote Originally Posted by SpeedFreek View Post
    I still think this is tenuous, to say the least. The 2 mark answer might just be wrong, or misleading.
    I am worried that the 2 mark answer is incorrect too....anyone else agree ?
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