From: Danger Hull (tdh23@dana.ucc.nau.edu)
Date: Fri Mar 31 2000 - 20:14:48 MST
Thanks for your response. The reason I suppose we can see stars from the
earth is because there are no very large objects reflecting massive amounts
of sunlight in our view.
Thanks Dana,
Tom
>>From Phil Plait's website
>(http://www.badastronomy.com/bad/movies/starwars2.html):
>
>"Bad: In a scene from high above Naboo, we see a fleet of Trade
>Federation ships
>silhouetted against the planet, and beyond that the sky is full of
>stars.
>Good: This is a common scene in science fiction movies, but ask yourself
>a
>question: have you ever seen anything like it in real life? The answer
>is no. When
>NASA broadcasts live scenes from outside the Space Shuttle, you usually
>see the
>Earth in vivid blues, browns, greens and dazzling white, but you never
>see stars at
>the same time. And if you can see stars, the Earth is tremendously
>overexposed.
>The reason for this is contrast. Stars are fairly faint, while the Earth
>(or the Shuttle, or astronauts floating in space) are very bright.
>They're sitting in full sunlight!
>
>So the Earth, when lit by the Sun, is many hundreds or thousands of
>times brighter
>than the stars behind it. When the astronauts set the camera to take
>pictures, they
>need to adjust it for that brightness. To expose the Earth correctly,
>they need to
>shut out most of the light hitting the camera, and the faint stars
>cannot be seen. If they adjust the camera to let in enough light to see
>stars (or more accurately, use a camera which amplifies the light of the
>stars), the Earth floods the camera with light, vastly overexposing
>itself. So even though the sky looks black, there will be no stars in
>the picture.
>
>I have received a few emails about this part, asking if the human eye
>would see
>things differently than a camera. In other words, the human eye is
>capable of
>seeing higher contrast than a camera, so is my objection still valid?
>Yes, it is. Ron Parise is a Shuttle astronaut who happens to work down
>the hall from me (how cool is my job?), so I asked him if he could see
>lots of stars out the Shuttle window when the sunlit Earth was below
>him. He said no; the only stars you can see are the very brightest ones,
>and only a few of those. As with a camera, the human eye only has a
>limited range of brightness it can perceive, and the Earth (or Naboo!)
>is so bright it swamps all the stars.
>
>As a side note, I'll add that some people, remarkably, think that NASA
>never
>actually sent men to the Moon; that all the Apollo films were faked. As
>a piece of
>key evidence, they cite that all the pictures taken from the Moon have
>no stars in
>them! So instead of asking someone who might understand photography,
>they jump
>to the conclusion that NASA managed to undertake the largest conspiracy
>in history.
>This is Bad reasoning in its absolute highest form."
>
>-Dana
>
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