why is the sky so dark at night

Why is the sky dark at night if the universe is filled with stars?

It isnt a question of ambient light, as i thought it was, it truly is a paradox.

en.wikipedia.org...'_paradox

Light travels at a constant speed in a vacuum. With stars at different distances, it takes different amounts of time for each star's light to reach earth. the black parts have stars, but the light hasn't reached us yet.

sorry to say that seems a little crazy.
the start are billiions of miles away. so lets assume that the stars are constantly being created and dieing.

it may take another thousand years before we see the light from a newly formed star. if you get what i mean. the light you see from the stars at night can be thousands of years old depending on their distance. so the star you sit and stare at during the nite could have all but extinguished a hundered years ago and you won't know for another nine hundered years.

if you get my drift. if all the stars were created simultaneously then perhaps we would get a very bright starlit nite. but because the universe is so large the light from a distant star is the equivalent of a spark from a lighter in the middle of a dark stadium and that is why the night cannot be illuminated by the stars.

Oh please tell me this is a p### take post? whys the sky dark at night? please? your kidding right?

Ok, the point about space being filled with stars..where to start. Yes they are bright, but think of the distances involved... the amount of time light has to travel to get to us.. Ok heres it real simple: Take a torch and a friend. Shine it at him when close to them, and then walk back and see if its still as bright as close by. As you travel away it appears to be dimmer because of diffusion of light in the air, and because of the energy needed to 'carry' over distances. A bright light close cannot appear to be the same brightness over very very long distances. We on earth have this problem because of the atmosphere being really thick and diffusing light effectivley, and the stars being far far away.

If how ever you climb above 10 thousand feet altitude you will notice the stars are really really bright due to the thiness of the air. But its still dark at night because of that. Its night time!

lol would you read the article, mad? jeez maybe im not as "enlightened" as you guys on the subject, im just asking a question

ivan im not laughing at you, but at the wickie post about it being a paradox

Oh man this is why its free, because all and sundry can post there ...ROFL.

Light from stars only has a certain 'reach' before it is undetectable to the eye, to telescopes and then to machines ie IR / night vision scopes ect.

Any soldier will tell you that if you look at the sky on a clear night with a nightscope, the sky is like a blanket of light - but with the naked eye its dark. Its all a question of what you use to view the sky. Theres no paradox - Night is dark because of lack of light for the eye to use.

Not sure what you mean.

I do not think there is any sort of paradox...

It is due to the fact that the other stars are so far away from our planet.

Atleast that is how I always saw it.

This area of space in which the Earth resides has been around just as long as the area of space in which the stars billions of light years away reside...( that must mean that the light has already reached us! approzimately 13.7 bilion light years... who really knows how old it is? It could be older! The older it is... the more time light has already had to travel!) it isn't the fact that the light hasn't made it here yet... it has to do with the atmosphere of the Earth, the way that the eye actually see's light, the scattering and dissapearance of light into black holes, the position of the stars and galaxies alignments and your reference point from Earth. That drawing is innacurate. When the moon passes directly behind the Earth and the sun, it is a new moon, not a full moon.(that means it is completely black because no light is reaching it) Look at a lamp, then put the back of your head to it and look away .. you notice the difference? That's why it gets dark at night. Oh wow, and forgot to mention that stars have dust and planets around them too! Anything that gets in the way of the light just once! Messes up that beam of light for it's whole trip... can you see it degenerating over time now?

[edit on 26-2-2006 by dgoodpasture]

Originally posted by Johnmike
Not sure what you mean.

Isnt that a picture of a Lunar Eclipse? Hows the moon lit up?? Is the Luxor Hotel and Casino pointing at it?

If the Universe had been around for a lot longer the sky would be just as bright at night as it is during the day. Because in every direction theres a star, and their light would have reached us.

You're also forgetting that the universe is constantly expanding, and expanding fast at that. The implications of this is that some of the light from the furthest stars and galaxies get red-shifted so greatly that it ends up in the electromagnetic frequencies that our eyes can't detect.



Click the pic to learn about the electromagnetic spectrums.

[edit - to add pic and link to electromagnetic spectrums]

[edit on 26-2-2006 by Beachcoma]

I haven't read the Wiki-article, but I know the paradox in question.

Essentially it goes:

"If the universe is infinite in size, and infinite in age, then not only should we have a perfectly bright and white sky, but we should all be cooked to death."

The paradox is solved by the universe being finite in either size or age.

If the universe is finite in size, then there's only so much light that stars can give out, and not every patch of sky will have stars in it. We have found this not to be the case - and that, essentially, every portion of the night sky has stars (most just too dim to see).

The other solution is that the universe is finite in age, with stars being born and deing. In this case, some sections will appear empty at least for a time.

We end up with just a few photons from extremely distant stars hitting us instead of the amazing number of photons hitting us from nearby stars, and the uncountable number of photons hitting us from the sun.

So, why is the sky dark? Photons per area. The photons per area of certain spaces in the night sky are greater than in others - sometimes by a lot more. Go far, far away from other sources of light - miles and miles away from any city - and you'll start seeing a LOT more stars, as well as the Milky Way.

The further from other light sources you are, the more stars you'll start to see, as less other light gets in the way.

Why, once I was out in a boat on Huron Lake... Marianne Cove it was... not that far from Manitolin Island. It was a September night - cold and windy as hell. But no moon, no clouds, no interferring light.

The Milky Way, my friends, was WHITE. Not blue, not cloud-ish, but WHITE. It was so bright, that one could see the massive dust-clouds that rimmed it. The bulge was enourmous, like it would swallow the sky. You truely understand why it was called the Milky Way... and just how MASSIVE it is. Incredible really. I've never seen it like that before or since.

If you go very far away from city lights, and give your eyes 30 minutes to adjust to your surroundings, you will find that the sky is not dark at all, it is filled with millions and millions of stars, and some of those things that look like stars are galaxies filled with millions of more stars. It is actually very bright, and you can observe things all around you here on earth from that light alone.

A drop of certain chemicals which dilate your pupils will make it even brighter.

There is a reason we call our galaxy the milky way, and it is not because of a drip of starlight, but because it is like a great gushing stream of it.

Darkness is really a matter of perception, try a pair of night vision goggles for example of this.

The Universe isnt empty. It is filled with dust and gas, those being the major blockers of light that shines from anywhere, that includes intergalatic and our own galactic debris. This is why we cannot see through the disk of the Milky Way.

Only the very brightest stars have the light intensity to cut through the "fog."

However on other bandwidths, EM radiation is very much blocked or not really bothered at all by dust and gas. This is why radio is such an excellent means of communication is that very little can block it, except a million ton mountain or a sheet of thick lead, which blocks virtually everything.

Milky way galaxy is called the Milky Way because of the shape our galaxy takes is a spiral shape.

Originally posted by EarthUnificationFrontier
Milky way galaxy is called the Milky Way because of the shape our galaxy takes is a spiral shape.

Huh? How did you reach that conclusion?

Anyway, the ancient egyptians thought that the Milky Way was a river of milk in the heavens. That shows how bright the galactic plane is. We don't really see it now because we mostly live in urban areas where there's plenty of light polution -- the glare stops us from seeing it.

My reasoning is the same as why a laser beam fired at the moon might not be seen - the light particles spreading out so much, hardly any enter our eyes.

It loses it's intensity the further away it is, just as a flash light does.