Deep sky, how much of its depth and height

[sunofsky]

no one can answer this question of "how this universe is horizontally big, and vertically how much it is long". thousands of years later also the answer will be unanswered.

there were mostly two objects in this space before the big bang happened, may be that two objects covered the whole portion of this or partly of the sky. there are many possibilities. later the bigbang theory was accepted by the world, but yet many questions are unanswered.

what is your opinion about this sky.
will its blue color remain forever..

sunil

[Dragon Star]

Hi Sunil, I am going to see if I get your questions.

no one can answer this question of "how this universe is horizontally big, and vertically how much it is long".

Thats right, because the universe is so big, and it has so much mass it twists and turns unpredictably from the warp of space time, we will never know exactly what it looks like...

there were mostly two objects in this space before the big bang happened,

Well. before the BB there was no space, BB created space as a result of rapid expansion from a singularity.

Also the "sky" as you say is nothing more them the visual part of our atmosphere, with stars that are behind that in the background.

The "blue sky" is caused from the different elements that make up our atmosphere, when the Sun goes Red Giant it is predicted to swallow the first 3 planets, that would certainly end the "blue sky".

[sunofsky]

thanks for the reply Dragon *.

[stuart]

Originally Posted by sunofsky

no one can answer this question of "how this universe is horizontally big, and vertically how much it is long". thousands of years later also the answer will be unanswered.

Yep, pretty much what Dragon Star said. But, you can define the visible universe which is the universe that we have any hope of ever seeing due to the finite age of the universe and finite speed of light. If just going by these, then our "horizon" is a sphere about 13 billion light-years in radius, which is as far as we can see because light from farther places hasn't had enough time to reach us. But, we can only see back to about 300,000 years, due to the Cosmic Microwave Background radiation, so the sphere is [however old the universe is]-300,000 light-years in radius. A good website explaining the CMB radiation is http://map.gsfc.nasa.gov/ .

what is your opinion about this sky.
will its blue color remain forever..

The sky appears blue because of the gas and dust in the atmosphere. It acts to scatter shorter (bluer) wavelengths of light, while scattering longer (redder) less efficiently. So, as sunlight passes through the atmosphere, shorter (purple and blue) wavelengths are scattered more than longer ones. Thus, the sky appears blue because the scattering makes it appear as though the blue light is coming from the entire sky.

This is why sunsets and sunrises appear red -- the longer path length through the atmosphere (the light's going through 5 or more "atmospheres") scatters the longer wavelengths (think of it as one atmosphere scatters 5% of yellow light, so 10 atmospheres scatters 50%) more, and so all that really filters through from the sun is the red.

This is also why umbral lunar eclipses appear to be red: The only light that can reach the moon has been bent by Earth's atmosphere like a lens, but it's also been filtered by it, so only the red light is left.

[Dragon Star]

Originally Posted by stuart

Yep, pretty much what Dragon Star said. But, you can define the visible universe which is the universe that we have any hope of ever seeing due to the finite age of the universe and finite speed of light. If just going by these, then our "horizon" is a sphere about 13 billion light-years in radius, which is as far as we can see because light from farther places hasn't had enough time to reach us. But, we can only see back to about 300,000 years, due to the Cosmic Microwave Background radiation, so the sphere is [however old the universe is]-300,000 light-years in radius. A good website explaining the CMB radiation is http://map.gsfc.nasa.gov/ .

Just a point to poke out there....

Problem with the light theory of Universal size is due to the expanding space/time, the speed of light was once much faster then it is today, meaning that the visible universe is much more vast then previously thought. And it is difficult to judge just how much light has slown down from BB, it could be as much as a few billion years...

[sunofsky]

what dragon is saying that is true, stuart.

sunil