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B Midnight Sun in the Arctic

  1. Oct 11, 2016 #1
    can anyone explain the Midnight Sun occurring in Arctic region. Why it happens and is it possible on a globe? indexas.jpg
     
  2. jcsd
  3. Oct 11, 2016 #2

    DrClaude

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    Staff: Mentor

    It happens because the axis of rotation of the Earth is at an angle (other than 0 or 90 degrees) with respect to the position of the light source.
     
  4. Oct 11, 2016 #3

    phyzguy

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    Suppose the Earth's axis of rotation pointed at the sun (Uranus is actually close to this). Do you see then that if you were on the north pole that the sun would be straight overhead and would not move as the Earth rotated? If not, try getting a globe and pointing it at a light bulb. Then tilt the axis away from the light bulb, but still pointed near the sun. Then the sun will describe larger and larger circles around the zenith (the point straight up). This is the situation for the Earth.
     
  5. Apr 30, 2018 #4
    My question is on the physics of this observation. If the earth is spinning, why doesn't the sun simply move to the right, then stop and move left, then right, and so on? The footage of the midnight sun shows the camera continuously panning to the right to keep the sun in view. How is that possible? As the globe spins, pretend you start at 3 o'clock and are moving counterclockwise...as u spin towards the 12 o'clock position, the sun arcs and moves right from our perspective, and continues this path until we approach the 9 o'clock position. It's at this point, as we begin to move from 9 o'clock, towards 6 o'clock and back to the starting 3 o'clock positions that the sun would appear to move left....not in a continuous line to the right only.
     
  6. Apr 30, 2018 #5

    phyzguy

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    I don't understand your confusion. Suppose you are standing on a spinning merry-go-round and there is a street light on your left. The merry-go-round is spinning counter-clockwise viewed from above. The street light will move from being on your left to being in front of you to being on your right to passing behind you until it is on your left again. But if you keep panning a camera to keep the street light in the view finder, you will keep turning to your right at a constant rate forever. Where is the discrepancy? If you don't believe it go down to the playground and try it.
     
  7. Apr 30, 2018 #6

    stefan r

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    Gold Member

    Most merrygorounds are not angled. This video has the view from a saddle spinner at 2:00. You can see the horizon go up and down similar to the ecliptic plane in the arctic.
     
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