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Stars beyond earth

  1. Jul 25, 2012 #1
    How come in pictures taken from space, we cannot see stars or the sun?

    Is it the atmosphere that allows us to see them?

    s122e010982.jpg


    Click on image to make bigger
     
  2. jcsd
  3. Jul 25, 2012 #2

    Ryan_m_b

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    It's due to how exposure in photography works. Essentially the stars are outshone by the planet.
     
  4. Jul 25, 2012 #3

    phinds

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    This is only true if the earth is in the picture. Haven't you ever seen pictures from the Hubble Telescope?

    Also, if the sun is in the picture you WILL see it.
     
  5. Jul 25, 2012 #4

    Drakkith

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    The brightness of the Earth in the photo requires a very very short exposure time for the camera. (That's how long the shutter is open and letting light in) This exposure time is much too short to record the background stars, which are FAR dimmer than the Earth is.

    The Sun isn't visible because of two things. First, the camera isn't facing the Sun so we don't see it directly. The second reason is that there isn't any air in space (or actually very very little) so the sunlight isn't scattered like it is in the atmosphere. That is why the sky is blue, the sunlight is being scattered by the air and the blue end of the spectrum is scattered more than the red end.
     
  6. Jul 25, 2012 #5

    mfb

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    You can observe the same thing in images from the Apollo missions. If the camera would be sensitive to stars, the earth (or the moon) would be just a big overexposed area of the photo.
     
  7. Jul 25, 2012 #6

    russ_watters

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    You can also observe the same thing taking nighttime pictures with a flash on earth.
     
  8. Jul 25, 2012 #7

    davenn

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    The sun is visible from space...
    why would anyone say it isnt ??

    there are many videos on the net etc of astronauts videoing sunrise over the limb of the earth

    just one pic done from the Shuttle Discovery .....

    attachment.php?attachmentid=49324&stc=1&d=1343266555.jpg

    Dave
     

    Attached Files:

    Last edited: Jul 25, 2012
  9. Jul 25, 2012 #8
    Hey thanks for the replies, and yes phinds I have seen Hubble telescope pictures.

    I seen this picture on another forum, they were trying to say that all satellite photos are faked, since you cannot see any stars, this sounded ridiculous. I didn't know the real reason why though, so I decided to ask the people who know the most.
     
  10. Jul 26, 2012 #9
    I recall seeing a video of the earth from orbit at night and was definitely able to see stars.
     
  11. Jul 26, 2012 #10

    mfb

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    At night, the earth is darker by some orders of magnitude, therefore the difference between earth and stars is not so large. You can expose photographs (or videos) longer / with a larger aperture, which allows to see stars.
    Here is a beautiful video. It ends as soon as the first signs of daylight are visible.
     
  12. Jul 26, 2012 #11
    It would be pretty easy to add fake stars to the black background of a fake picture.
     
  13. Jul 26, 2012 #12

    phinds

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    You are REALLY wasting your time dealing with crackpots. Ignore them and move on.
     
  14. Jul 26, 2012 #13
    It is easier said than done, they are making me upset, talking about space and physics and NASA as if they were there.
     
  15. Jul 26, 2012 #14

    Drakkith

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    Most people are dissuaded as soon as you throw a little bit of REAL science or math at them. The more stubborn folks simply can't be reasoned with. Don't let them get to you, for there is nothing you can do about it. To them you are either with them or against them, for they cannot possibly be wrong.
     
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