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If Earth had no colloids (Don't take LIFE into account) or any kind of scattering medium (like atmosphere) that promote to Tyndall effect, how would we able to receive the sun's rays? In the other way, How would the sun rays or light from any interstellar object reach or appear to us? (just like a distant star?)

Is there anything that I missed here? (Please comment)

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Maybe you mean how light can travel in intergalactic space which is "almost" vacuum? If that what you meant, there is no need for any scattering medium, it will only cause interference and diffusion of light, nothing more, while light which is actually electromagnetic field needs no medium or "aether" (this how it was called before Einsteins relativity) to travel from place to place, you can't put light wave in analogy with sound wave or the waves you see on water, because they has different nature and needs medium alike light, – TMS Sep 13 '12 at 13:04
anyway to make it more intuitive you can think about light as a flow of particles, each one called photon (anyway that doesn't means that it is not a wave) and those particles can travels through vacuum without any medium. – TMS Sep 13 '12 at 13:04

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We know how it would appear without any scattering medium, the experiment has been done:

Astronaut on moon

The large distance to the sun creates almost parallel rays of light and without scattering everything that is not directly hit by sunlight will be pitch black, such as the shadow of this astronaut. Only the little bit of surface reflections from the dust are lighting up the front side of him.

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Were there lights on the exterior of the lander? – Mark Betnel Sep 13 '12 at 14:11
@MarkBetnel: I am not sure, I guess not and as there are basically no shadows on the front side of the astronaut the light can not come from a point source, e.g. a single light but more likely from reflected/scattered light from the ground and the astronaut taking the picture. – Alexander Sep 13 '12 at 15:15

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