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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- Savannah S.about 12 yearstwo things i learned were, that the universe is expanding and that in a billion years people might not be able to see stars except through an infrared telescope.
- leila v.about 12 yearsOne fact I learned was that our universe is 13.7 billion years old. Another fact I learned was our universe is pushing the stars away. My opinion on this is the stars are so bright that we can see them.
- Savannahabout 12 yearsThis is really cool! I never knew that there were so many different possibilities for why we can see stars and the moon at night, or even if the sky is truly dark. It informed me of all the things that the scientist are doing in our universe every day to learn and teach us new things.
- Michelle Kabout 12 yearsOur universe is 13.7 billion years old and that the ever growing universe is pushing stars away and thats why the skies go dark. I think its quite unteresting that the universe is still growing and i want to know if it has an end now.
- Justinabout 12 yearsDid you ever wounder why the sky goes dark at night? Well there is a perfectly good explanation for that. At first astronomers use to think it was because it was dust. But not far after they discovered that the dust would effect the sun also so that theory was wrong. Their next theory was that almost all the stars where where stacked behind each other we all know that theory is wrong but they did not. as soon as they found out that was wrong they found out that it had to be that it had to be distance. That's why the sky gets dark at night.
- Davidabout 12 yearsI wonder how scientists figured out that the movement of earth didn't cause the sky to turn to turn pitch black. First, the sky turns pitch black at night. The sky turns pitch black because at the edge of the visible univers it is pitch black causing the night time sky to look black. Second, You could ask a kindergarterner why the sky turns black at night they would '' Because earth spins like a top''. Really Heinrich Olbers discovered that it is because of the edge of the universe. Scientists discovered that the night time sky is because of the edge of the universe
- Gregabout 12 yearsThat would be really boring if there were no stars in our render distance. One reason is that many people like to watch the stars laying on a hill but if we could not watch the stars we would have lot less creativity. That is why we would be really bored.
- George Wangabout 12 yearsWow, I never thought of that. I'm the scientist in my grade, though.
- Ali sabout 12 yearshow cute!!!:)
- niallabout 12 yearsi didn't understand that
