If the universe contains trillions of stars then why isn't the sky as bright as the sun at night?

Answer 1

Human beings are able to see only a small part of the electromagnetic spectrum known as visible light. The sun emits most of it's radiation in the form of visible light which makes it no coincidence that humans have evolved to see only visible light. When radiation passes through matter in space the higher energy photons are filtered down to lower energy wavelengths. Light from a distant galaxy might pass through a cloud of gas or dust on it's way to earth and essentially making that galaxy invisible to the human eye. Rattlesnakes can actually see heat differences which means that they are sensitive to infrared radiation which varies with thermal variations. Infrared radiation cannot be seen with the unaided human eye. Aside from light being filtered down in to invisible wavelengths, the universe is finite, it doesn't go on forever which is a big contributor to why the night sky is dark. Hope this helps.

Answer 2

This is known as Olber's paradox (as others have said).
His question went something like this:
"If the universe is very large, then the light from stars will decrease with increasing distance from us; but the number of stars will increase by the same proportion. Therefore, the whole of the sky should be as bright as the sun, (which would make life on earth impossible).

An explanation is that, although the universe is very large , it is also expanding, and so the light from distant stars becomes weaker as it reaches us, and once stars (or galaxies) pass beyond a certain distance (the 'event horizon'), then light from those stars will never reach us at all.

This answer to Olber's paradox was a turning point in astronomy, because this paradox caused great theoretical difficulty until it was realised that the universe was expanding.

Answer 3

The star light energy that reaches the Earth from the Cosmos, is about 1.1 x10^-11 joules per second per stereradians. The reason is not because light travels a long distance ,but because in the large volume of the Universe, dissipation of light occurs.Hence a thining out of photon rays.

The Universe appears black to our eyes because very little reflection occurs from space dust. WE can only see with our eyes if light flux enters our eyes.

We cannot see the Sun's rays moving over the earth at night; but only seen if there is a moon to reflect the Rays.

The reason we dont see the rays of the sun permeating in space is because light is made up of micromasses so small, that they cannot be shadowed.

Believe it or Not =light is invisible.That is the basic reason that the space of the Universe appears dark even thought so many photons are floating in it.

When a celestial body like a star or Galaxy loses the micromasses of light they have to go some where. Where? In the astronomical volume of the Universe.But since the Universe is a finite contained system ,light does not escape the Universe.
The reason is that the Universe is so massive that even light cannot escape from it.

So the Universe can be considered as a Dark hole somewhere in our Creator's Heaven.

Answer 4

The sky is indeed full of stars. Most are so very far away their light is way too weak to activate the light sensing nerves in our eyes. The further away you get the further back in time you go. Go far enough you reach the point where the universe was actually dark, before the first stars formed. If you could see the spectrum at the level of the cosmic background radiation left over from the big bang, the sky would be thousands of times brighter than noon.

Answer 5

there is no person vibrant action picture star it somewhat is often interior the evening sky, because of the fact the Earth rotates as quickly as each and every 24 hours, and rounds the sunlight as quickly as ever twelve months. So the stars are under no circumstances interior an analogous place from evening to evening. If, like maximum human beings, you do no longer pay plenty interest to the stars, you in all probability does not be conscious how the stars and planets substitute from hour to hour and from evening to evening. So your "brightest action picture star" must be absolutely everyone of a pair of dozen vibrant stars seen maximum nights, or, even plenty greater probable, a vibrant planet like Venus or Jupiter. it ought to additionally be the international area Station, which now outshines each and every little thing different than the sunlight and Moon. there is one action picture star that's constantly interior the sky interior the northern hemisphere, Polaris, the Pole action picture star, in spite of the undeniable fact that that's a reasonably insignificant 2nd magnitude action picture star, with regard to the fiftieth brightest action picture star interior the sky.

Answer 6

Because the light from most of the stars etc is too dim for our eyes to register.
If you want a better look, get a film camera with a 35mm lens (digitals are no good for astronomy), set it on a so;id tripod , point it at the celestial pole and make a time exposure of about 3 minutes. Use the fastest film you can get (3200 ASA).
When you develop the picture you will see that there is hardly any space visible between the star images.

Answer 7

Yes this is Olber's paradox. The simple answer is that the Universe has not existed for an infinite amount of time, and therefore light has had a finite time in which to reach Earth.

Answer 8

This is known as Olbers' Paradox. Try Googling it. Basically, there is dust in the universe, which blocks enough of the starlight to make the sky dark.

Answer 9

Because the stars are so far away. Trillions of anything dumped into something infinite is not that much.

Answer 10

I think the Sun is our NEAREST star in the entire universe......

Even when the sun goes to sleep at night, the far-off stars simply twinkle faintly...