Pangaea | Earth geological and climatic history | Cosmology & Astronomy | Khan Academy

Pangaea - the idea of Pangaea and some of the evidence behind it. Created by Sal Khan.

Cosmology & Astronomy on Khan Academy: The Earth is huge, but it is tiny compared to the Sun (which is super huge). But the Sun is tiny compared to the solar system which is tiny compared to the distance to the next star. Oh, did we mention that there are over 100 billion stars in our galaxy (which is about 100,000 light years in diameter) which is one of hundreds of billions of galaxies in just the observable universe (which might be infinite for all we know). Don't feel small. We find it liberating. Your everyday human stresses are nothing compared to this enormity that we are a part of. Enjoy the fact that we get to be part of this vastness!

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[tiathomas]

This video is very fascinating! Thanks!

[camelCaseFTW]

i remember watching this on Bill Nye when I was 8. I just love watching your videos even if I have already learned it.

[MissCNN]

thank you for making this video, it really helped me with my homework and science

[LinkinPark]

i wouldnt mind this guy being my professor...

[mike]

Anytime someone asks me where I'm from, I tell them Pangaea. Technically it could be true :)

[artembluntzki]

Earth has been the same size for a couple billion of years now. All the excess lithosphere is digging under other lithosphere and get pushed down into the Earth's mantle, where it is melted.

[ghostXsafari]

KHANACADEMY and people of youtube, there is also theories that the earth has been growing!

it makes sense that the continents are only going stay apart as over millions of years the earth is getting bigger!

[artembluntzki]

I think it might have been smaller the first billion of years during the Hadean era where the earth was still creating layers (molten crust -> basalt crust -> ocean 'crust' -> granite crust).

[derman]

@barakameek Ahh I see your image now. It was fuzzy but now makes more sense. Perhaps the Earth did wobble quite a bit more then than today. I wonder if extra solar planets have been observed to act in this way. What is your position on the early Earth expanding theory?

[spaceghost]

sal, do a projection into the future, that would be cool

[DTK]

This same concept of reversing the movement is correct but let's do the same with all the oceans given the age of the ocean floors.  By doing so, all land connects nicely, not just the Atlantic Ocean.  Meaning, all continents were one without the oceans that are only a few hundred million years old.  The expansions of all oceans are evident.

[lokynokey]

We can actually find fossils in Antarctica?

[memejawd]

@DCowdenHMB this video can most likely be found on his website. Look there if you want a comment-less version (still comments there but it only shows around one or two and those are usually top comments)

[tagasmr]

Omg had to do this for silence work during social distancing:(

[senatorped]

Great. The only problem is that the spreading on the ocean floor happens in the Atlantic .... AND the Pacific. And the other ocean floors as well. So you can't say that millions of years ago the Atlantic was closed up but the Pacific was wide open. They both were/are spreading at the same time.

[JJRulez]

This my science homework.... at least I dont have to write about it :D

[Madpolis]

@JudeAballer I learned plate tectonics in 6th grade!

[Ozow]

i think its actually that it used to be smaller, and got bigger, but it stopped some time ago. i think thats the theory hugh owen proposed

[artembluntzki]

what about mid-ocean ridges, trenches and subducting plates?

[theburger]

I have learned plate tectonics in 4th grade