From: Dana Hedberg (dah@signalinteractive.com)
Date: Fri Mar 31 2000 - 17:47:20 MST
Danger Hull wrote:
>
> Anyway, I must admit I was confused about something he called a usual error.
> I understand the sound in space, but I don't understand seeing stars out of
> windows...... I would appreciate it if one our more astronomically trained
> members might help with that. Is he saying you can't see stars in space or
> what am I missing?
>
> Thanks
>
> 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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