This is a spin-off from the APOD 23 april 2008 blog "Full Moon Next to Venus". I believe this subject deserves a discussion of it's own. That earlier discussion brought up the idea that here on Earth we can see the stars at night because the Earth's atmosphere spreads the light to such a degree that our eyes can see the stars. Apparently in the absence of an atmosphere our eyes cannot get enough light to see such small objects. Time exposure cameras can, however, get enough light to make an image without being aided by an atmosphere. Can astronauts on the International Space Station see stars?
I'd appreciate it if someone in the "know" would ring in and explain the absence of stars in non time exposed photos of the Space Station or non time exposed photos taken FROM the Moon.
SEEING STARS
If you go out at night to a well lighted parking lot (note the dark grey ground) and look up, you will only be able to see the brightest stars in the constellations but none of the fainter stars. If you walk out of the realm of the lights and look up, you will see many stars If you take a picture of the dark sky with the iris speed set for day time images, you will see no stars in the image.
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iamlucky13
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I don't think it's true, due partially to the fact that I've never heard it before, and partially due to my understanding of the way the eye works.
It's true that we can't spatially resolve stars as discs, but even as point sources they still stimulate the eye, and the eye has it's own imperfections that tend to expand them from a perfect point. The same amount of light is entering the eye. The difference is how focused it is. It's extremely improbable that all the photons entering your eye from even an extremely small object like a star would consistently miss all the photo receptors in your eye.
Regarding the guy who toured Mauna Kea (sp?), I suspect either it was early evening when they began their descent and more stars became visible as the sky darkened, or he was simply less aware of the number of stars because they didn't appear to twinkle. Or maybe the tour guide was full of it and he took him at his word without ever consciously thinking about it.
Here's a little more on the topic
http://curious.astro.cornell.edu/questi ... number=174
Phil Plait of badastronomy.com answered the question of whether astronauts can see stars in space, but unfornately he doesn't provide a reference for his key quote "Astronauts have reported being surprised at how steady and clear the stars look.."
http://www.badastronomy.com/mad/1997/seestars.html
It's true that we can't spatially resolve stars as discs, but even as point sources they still stimulate the eye, and the eye has it's own imperfections that tend to expand them from a perfect point. The same amount of light is entering the eye. The difference is how focused it is. It's extremely improbable that all the photons entering your eye from even an extremely small object like a star would consistently miss all the photo receptors in your eye.
Regarding the guy who toured Mauna Kea (sp?), I suspect either it was early evening when they began their descent and more stars became visible as the sky darkened, or he was simply less aware of the number of stars because they didn't appear to twinkle. Or maybe the tour guide was full of it and he took him at his word without ever consciously thinking about it.
Here's a little more on the topic
http://curious.astro.cornell.edu/questi ... number=174
Phil Plait of badastronomy.com answered the question of whether astronauts can see stars in space, but unfornately he doesn't provide a reference for his key quote "Astronauts have reported being surprised at how steady and clear the stars look.."
http://www.badastronomy.com/mad/1997/seestars.html
"Any man whose errors take ten years to correct is quite a man." ~J. Robert Oppenheimer (speaking about Albert Einstein)