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What do the stars look like from space?

  1. May 7, 2012 #1
    From the first few hits I found on the internet, here's what I gather:

    They are the same as they appear from Earth, except they do not twinkle (no atmosphere). They are like small points of light. The contrast between stars and black background sky is also greater than on Earth.

    They can be different colors: red, blue, etc, though I'm not sure if this detail can be ascertained easily (i.e, do a lot of them show thier natural color or only a handful? Are a lot of the stars different colors, or would most of them appear white?).

    I've also heard that 3000 stars or so are visible with the naked eye from the ground (in clearest weather). Would this number go up dramatically if I remove the atmosphere? I presume here that the atmosphere blocks out lots of faint stars. Or would the atmosphere not filter out that many faint stars, and the density of stars would appear essentially the same as it as from viewed from the ground?


    I saw this opinion:
    you can't see the stars from space because the sun washes them out, so space appears black. (Not sure how much I believe this one) The sun is bright enough to wash out stars in the daytime, but a lot of that is scattering by the atmosphere. I would imagine that in space, the sun would still have its prominent brightness, but looking in a direction opposite the sun you should see lots of stars.

    Anyway, which of these correct (if any), and if anyone has a good website (or even software program) to show what stars look like in space with a naked eye, that would be great. I failed to find one. I understand that camera flashes in space wash out lots of stars or are used to emphasize astros and shuttles and such.
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  3. May 7, 2012 #2


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    Outside of the atmosphere you would indeed see more stars, as the atmosphere is not absorbing or scattering any light. I don't know the actual number. The Sun would not wash out any stars unless you were looking in it's direction, as there is no air to scatter the sunlight into different parts of the sky.

    Generally, when we take a picture of something in space that is lit by the Sun the object is so bright that the exposure time is not long enough to capture any stars. This same effect is the reason that no pictures of the astronauts on the Moon show any stars either.
  4. May 8, 2012 #3
    One difference that was always brought to our attention was that the stars would not twinkle since the twinkling is merely the result of the atmosphere moving between us and the observed stars. In the Caribbean the night sky is awe-inspiringly star studded as opposed to the urban areas in industrialized countries where the smog and city lights permit only a few to shine through.
  5. May 8, 2012 #4


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    You can see over 6000 stars from earth with the naked eye in good conditions. In space you could see well over 20,000 stars, including a number of deep sky objects.
  6. May 8, 2012 #5
    The deep-sky object Andromeda Galaxy can be seen from the earth's surface with the naked eye as well.
  7. May 8, 2012 #6
    Hi Chronos,

    I wanted to respond to this: "...including a number of deep sky objects." What deep sky objects? That would be fascinating to know, something besides just stars with real structure. Do you have a reference I could look to? That would really be great.
  8. May 8, 2012 #7
    You don't consider the Andromeda Galaxy a deep sky object?

    Deep Sky Objects
    Last edited: May 8, 2012
  9. May 8, 2012 #8


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    On earth, magnitude 6.5 is generally considered the limit for the unaided eye. In space your visual limiting magnitude is about a magnitude fainter than on earth, and you always have a dark sky. The Messier catalog [re: http://en.wikipedia.org/wiki/List_of_Messier_objects] [Broken] will give you an indication of what additional objects you could expect to be detectable from space.
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  10. May 9, 2012 #9


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    Colors: The stars have different colors, and with telescopes on earth it is easy to see them. However, our eyes need some minimal intensity to see different colors (more than for a greyscale observation), therefore objects have to be very bright to see their colors. Some stars could have some observable colors, and mars has this even on earth.
  11. May 10, 2012 #10
    The appearance of stars depends on the relative position to them. If you are up close like here on earth it would look like the sun. Many of them can be bigger or smaller depending on the size; our sun is a medium size star. They can also have different colors like red, orange, white, gray, yellow, green or blue depending on the temperature. Blue being the hottest and red the coolest. Now if they are far well you all know what they look like just as we see them in the sky. As in size there are two ways to think about the size of the earth with respect to the sun. First way, the Sun's diameter is about 100 times that of the Earth. So, you'd have to line up 100 Earth's end-to-end to stretch across the face of the sun. Or you can think about it this way. If the sun was a bowl, you would need 100x100x100 = 1,000,000 Earth to fill it.
  12. May 10, 2012 #11
    Hi all,

    Those sites really helped. I got a lot of information from them.

    I did have one other questions. Is there a service, computer, software, etc. where, if you punch in the coordinates, it will tell you what objects are there, and what kind of telescope you need to see them? That would really be great, if it exists.
  13. May 10, 2012 #12


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    There following is a good site for seeing what's out in space and where. It works like google maps, you just click and drag to scroll around and you can zoom in and out. However these are all long exposure photographs and won't tell you if you can see them or not. But that is actually a bigger issue than you realize. The brightness of the background skyglow at your location can severely limit your targets, even with bigger telescopes. So if I tell you that you need a 4 inch telescope to see Messier 30 or whatever, and I observe from a dark sky spot, you may live in a big city and be completely unable to see it thanks to all the lights. See the issue?
  14. May 10, 2012 #13


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    One more thing about color. (Or 'colour' if you prefer that spelling.)

    If you were to rise above Earth's atmosphere, the stars would have a more bluish tint to them then they otherwise would when viewed from the Earth's surface, all else being the same.

    The sky is blue because atmosphere scatters lower-wavelength light. As a result, when viewed from the Earth's surface, the Sun appears yellow -- the bluish part of the spectrum from the Sun scattered, leaving yellow.

    The atmosphere has the same effect on the stars. On the surface of the Earth, they appear more yellowish than they would when viewed from space, all else being the same.

    So above Earth's atmosphere, the Sun's color would shift from a yellow hue to one much closer to white. Similarly, the tint of the stars would shift toward blue a little.

    (This should not be confused with Doppler blue-shift. That is totally different. The shift toward a bluish tint described here does *not* involve a shift in spectral emission/absorption lines. The spectral lines are unchanged. What I'm discussing in this post is purely a matter of atmospheric scattering [or lack thereof, when outside the atmosphere].)
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