The Real Reason Skies Go Dark After The Sun Sets
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Why does the sky go dark at night? You are all probably thinking that this is a question even a kindergartner can answer - The simple answer and the one that is pretty obvious is that as the Earth rotate on its axis it moves away from the sun and therefore, causes the skies to go dark. Sounds logical to us but what about the zillions of sparkly stars? Why don't they pitch in and make the sky all shiny?
This was a question that German astronomer Heinrich Olbers pondered over at length all the way back in 1823. There were many possibilities - Maybe the light from the stars was being blocked by dust, but then that would also have the same effect on the sun. Then there was that possibility that maybe there were just not enough stars or that they were all stacked behind each other - Both facts that we all know are not true.
After thinking about the conundrum at length, astronomer could only blame the darkness to one thing - the finite age of our Universe, or what scientists refer to as our Observable Universe. Since this according to the experts is estimated to be 13.7 billion years old, any light from stars beyond cannot be observed by us especially with our naked eyes, giving us the impression that the sky is dark.
While this phenomenon called Olbers' Paradox is still considered to be the primary reason for the lack of light, when NASA's Hubble telescope discovered that our Universe was still expanding, scientists realized that there could also be another reason for our dark skies - The ever-growing Universe is pushing the stars further and further away, so much so, that millions of years from now, humans may not be able to see any stars unless they use infrared telescopes, because the speeding stars do leave behind a streak of faint infrared light!
Still a little confused? Then be sure to watch this easy to follow video put together by 24-year old Harry Reich. Scientifically trained in physics, Harry is is now focusing on cinematography and creating a series of videos dubbed Minute Physics that makes science simple and fun to learn, for those of us not as passionate about the subject.
Resources NPR.org, math.ucr.edu
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180 Comments
- MMSHannahS3almost 12 yearsIn this article, 'The Real Reason Skies Go Dark After The Sun Sets' is obviously about why the sky goes dark after the sun sets. But it questions why isn't it bright if their are so many stars out "there"? It states that since there are so many stars and that space is always expanding, the stars sort of stretch with the expanding space. The farther away they become from earth or any planet, the redder they become. And at one point they become so very red that they become black and it has a specific name; "infrared". This leaves me wondering of why do they become red? Why not pink or yellow or any color? It is an amazing theory, not because it gives you a simple answer of why the sky turns dark, but why it doesn't turn bright if their are so many stars that somehow fill space.
jiyoon2446almost 12 yearsWow, how fascinating! This is an interesting article. Guys! Post some comments here.- swapmeetalmost 12 yearsThis guy should make more minute physics, it would make science SOOOOOOOOOO much easier to understand.
- MMSkaitlyn249almost 12 yearsthis article is about space and why it gets dark at night. The universe is practically pushing the stars back. So that would mean that in millions of years from now you wouldn't be able to see any stars in the sky unless you use a infrared telescopes. I thought this article was cool because i've never really thought of that question before. Now that I know about this I might even tell some of my relatives about it.
- MMSEmilyB11almost 12 yearsI think that it is cool that some people think stars are blocked by dust because the sky at night isn’t shiny, but the sun will have to be blocked by dust too because the sky in during the day isn't shiny. I think it’s a cool fact that you cannot see any light behind the stars. The reason we see that the sky is dark at night is because the stars block any light that is behind them. I think it’s cool and sad that the Universe is growing bigger and it's pushing the stars father back so in a million years people won’t be able to see the stars. I think this article is very interesting and filled with cool facts.
- hialmost 12 yearsconfusing...
bananakilleralmost 12 yearsuh... the earth turns on its axis and the stars cant lite up the sky cuz the milions of miles away- ashlyalmost 12 yearsoh okay, there must be another thing involved in this I'm still confused it doesn't make any sence.
southernbellealmost 12 yearsit makes sense. the universe is expanding, so stars get farther away all the time. the farther they get away, they turn red--INFARED. we cannot see infared light w the human eye. the farther we look with a telescope we see the older parts of the universe. THEREFORE the sky is dark.
tavianalmost 12 yearsyoure right
- mealmost 12 yearswhoops i feel there is something else to this
- mealmost 12 yearsfor some reason i feel that there of this that we just dont understand and get. there is more than we think out there.
