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by yaakov34
1435 days ago
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These objects are much too faint to see much of anything with human eyes. We can see them in astrophotography because the exposures are hours long (or weeks even, sometimes), and because telescopes gather more light than the eye per unit time, as well. This is why these nebulae look like billowing clouds - they are huge (light years across), so some light is absorbed as it crosses them, and some of the infrared light emitted by them adds up. And then we enhance the effect by taking very long exposures. If we actually went and stood near or even inside these nebulae, we would still be in pretty hard interstellar vacuum, and we wouldn't see anything. |
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