Why Is There Light On Earth But Space Is Dark?

Why does space look dark if the universe is full of stars? This was the question asked by Heinrich Wilhelm Olbers in 1823. From there came the famous "Olbers Paradox."
It tells us that, in a static and infinite universe like ours with infinite stars and infinite space, the night sky should be bright and without any dark region since the stars would illuminate every corner of the sky.
But why does the night sky look dark if infinite stars exist in the universe?

Whenever we look at the sky at night, we see some star beads on a dark background; this is because when on earth it is night, it is because the sun is illuminating the other side of our planet where it is a day.
But if this is the case... Why is only the part that points to the sun illuminated? In other words, why is it daylight on earth, but in the rest of space, it is dark?

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Credits: Nasa/Shutterstock/Storyblocks/Elon Musk/SpaceX/ESA/ESO/ Flickr

Video Chapters:
00:00 Intro
2:18 why is space dark?
5:07 space and time: the enemies of light
6:18 olbers paradox
7:27 expansion of
9:22 the light we can't see

#insanecuriosity #space #sky

[InsaneCuriosity]

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[YoungGandalf]

There's nobody in space, so it would be a waste of electricity to leave the lights on all the time.

[dr.a]

During the last full solar eclipse in USA, August 21, 2017, it was so weird to see bright stars and several planets during the day while the sun was obscured. Meanwhile out on the horizon it was full light. I only wished it lasted longer to observe in awe and wonder.

[damn]

The more we learn about Space and the Universe... It seems like the whole Simulation theory just gets stronger....

[judgedread-qt]

Seeing the sky at high altitude on a daytime flight never fails to amaze me - look down and it's regular blue sky, look up and it's black as night.

[Hiiamsamm]

Answer: because thats how the developers who made our simulation we live in wanted it.

[mishkosimonovski]

Light means energy (photons) reflecting from matter (atmosphere, plants, flowers, clouds, ocean, soil). As space is sparse on matter and energy....it's dark.

[entropybentwhistle]

Olbers didn’t realize that the universe isn’t infinitely old and light photons from stars have to follow the inverse square law (the farther you move away from a light source the less photons there are to fill the space) then navigate gases, dust and larger objects. It’s going to look pretty dark unless you’re close enough to a star to collect a massive number of photons. Think how bright our rocky neighbors the Moon, Venus and Mars are, and Jupiter and Saturn because of their size and gas composition reflectivity. Then Uranus, Neptune and Pluto had to be discovered by telescope because there’s not enough light reaching and reflecting to be seen by the naked eye back on Earth.

[BrendanDell]

Super interesting video! Space is full of never-ending questions and opportunities to learn- thanks for sharing this knowledge!

[D-Rock]

This could have been a 3 minute video. I heard the same information probably 5 times 😆 really stretched those 3 minutes past 10 hahaha

[TheRoidemortetfleur]

Nothing is faster than the speed of light. Three sentences later the Universe is moving faster than the speed of light.

[zakkusgaming]

Every time I hear 'Dark Matter that we know exists' I tune out.
We do not know if Dark Matter exists, it's still a hypothetical matter just like Aether.
If you're going to use Dark Matter as an education explanation of how something works, you have the responsibility to make it clear that it's theory, not fact.

[watermelonsprite]

I always thought that space was black because of how far and deep it really is

[kelseyissastar]

I love black space. It’s like deep water. Very calming. As above so below

[herbalheroine]

I feel like the simple answer to this question is “because the universe is massive. It’s like asking why is my house dark but the neighbor has his lights on.

[christopherjackson]

Please could you talk more on the idea of an "Infinite Universe"? It has to be the most frustrating question, making the existence of gravity no big deal by comparison

[mrsbluesky]

I took Astronomy 101 way back when thinking it’d be an easy A. Boy was I wrong.

[mikes]

The premise that there are infinite stars is wrong. The universe may be infinite (or at least continually expanding) but matter is finite. If matter was infinite that would mean more matter was constantly being created. And we all know matter cannot be created or destroyed, only change form.

[michaellong]

Our eyes have evolved to see only a very small part of the very wide electro magnetic spectrum ( for one example, Ham radio frequencies occupy another part of the spectrum. We certainly can't see that!). Our brains interpret what little part of the spectrum that we 'see' and separate the minute differences in each wavelength into what we now call colors of which white for example is just one color or wavelength. We in all our conceit have expanded our definition of 'light' to now include all the various wavelengths of the EMS even though our eyes and brains cant 'see' them. For example when we see pictures from the various space telescopes, what we often are looking at are computer created versions of what is actually there that have been visible color enhanced to differentiate the various wavelengths being received. Those telescopes are seeing wavelengths that we cant visibly see which are then converted to colors we can see so we can get an idea of what some distant entity (star, alien planet, clouds of gas) might look like ...if we had the ability to see at those wavelengths ...which we dont.

[happyrogue]

It's the "scattering" of light by atmospheric gases and not "reflection" that's responsible for the brightness during "day"!