Thread: RevTT invite for why is the sky dark at night?

Why is the sky dark at night?
bc of actully the sun goes down and the sky gets dark, bc of sun lights the sky and when it comes back up again it will be light.

I assume by sky, you mean space, and by dark, you mean black.

Space is black becuase there is nothing there for the light to reflect off of, thus providing something that can be seen by our eyes. We see the lights of stars, but the light beams are basically unhindered. The sky is not blue at night because there are no photons to interact with the atmosphere

Not really sure what you mean by counter arguments. There is a set answer to this question. Unless you're looking for theories as to why we see the sky as black, i.e. why is it considered black to our eyes, (which is really a semi-philosophical question) there are no counter arguments.

The reason the sky is blue during the day is because the sun's photons bounce off of the molecules in the atmosphere, and since each atom absorbs some of the energy of the photons and re-emits them (at different wavelengths) we see the sky as a separate color (in this case, blue).

pretty easy actually. this was a question for Remote Sensing quiz :D. However, i have RevTT ;)

Well of course putting it into my own words it would be like this :

The sky is dark at night, because the dark actually is space. During the day we see a blue sky because of the huge light of the Sun who illuminates everything. But at night, there is nothing that can iluminate the part of the Earth that is in the shadow. "Dark" means mattare that keeps the Universe altogether and there is so much of it that you see the stars and nothing around them just black collor.

Well I tried my best in explaining it

The sky is black at night because God switches off the light !! ( JK :P )

The sky is always dark, but at day time is blue because the sun illuminates our atmosphere

Originally Posted by Goo Ball

So what if I was a sceptic and was to say, the universe was infinite?

That's not a counter argument. In fact, you're supporting my argument because space can only be black if it is infinite. That is to say, if space was finite, and had an end, then presumably photons, (light) couldn't penetrate that wall, since it's the end of everything, and would have to bounce back. Then theoretically, we could see this light bouncing back, and after a long time (depending on how far away the end of the universe was) eventually the universe would become awash with light due to us see the constant reflections of starlight bouncing off the end of the universe.

Therefore, since this is not true, and the sky is black, the universe must be finite or infinitely large such that it would take a time period longer than the existence of the universe since the big bang for the light to travel to the end and back so we could see it. Or the universe could just be expanding faster than the speed of light, so the photons are constantly behind the "wall" at the end of the universe.


Nice, I just proved that the universe must be expanding, (as opposed to statically finite for the reasons i detailed above, and not infinite either since it was finite at the big bang and therefore must still be finite, albeit, expanding.)



Go me!