How we know about the earth's core | Cosmology & Astronomy | Khan Academy

S-wave shadow and P-wave detection patterns give us information about the core. 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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[Lishkabro]

A decade later and people such as myself are still learning. Thank you.

[YasuEntertainement]

Okay and how do you guys do it with planets?

[NitashaAslam]

I had forgotten how easy it was to learn with Sal :)

[cjayem]

awesome video. sure answered my question!

[onslaughtmp]

This gives me a much better understanding... Thank you!

[jonasianbuddy]

gosh how come i've never learned this before?
thank you Sal for teaching me :]

[gutiux]

wow sal i had like a million years with this question! THANX! keep em coming, cheers from costa rica

[ikris]

Hi! I'm your new subscriber here. This really helped me a lot, because my science teacher didn't much explained about the seismic waves. And again, I very much appreciate your help. 👍

[FreeTruthShow]

Thank you . Just what i was looking for. Though how did science assume there was a outer and inner core before the advent of seismology?

[prajwalgurung]

Thank you so much sir. I got curious how scientists found about inner cores of a planet & came here and you explained in a very good way. Thanks for fulfiling my curious mind. :
)

[brown.s_life]

Thank you so much Khan academy for all these sessions 😭

[azsrathud]

You are my hero!
Also, some intense math (calculus?) must've been had to indirectly measure the innards of the earth using curved lines.

[meepcaster]

This is the most straight forward non bs explanation. Thanks.

[numatichades]

Thank you now my project willbe an A for sure

[nottees]

Wonderfully clear explanation - appreciation rains down on you from me. How do we know that S waves only travel through solids?

[wadder]

Came here for a breath of fresh air after debating with flat earthers.

[Rianz]

quick question was this proven? and if it was can I have a link? or a book reference so that I can read additional info please.

[Rotceev]

Amazing and interesting video! thank you this is fascinating and informative. One thing bugs me. I'm no geologist, maybe that's why, but:
1. How those waves can travel this distance to be properely measured?
-I mean, even if they can travel this amazingly HUGE distance, how scientist distinguish thee quakes? I mean, the time delay would be soo big that the wave could be for example, coming from a weaker quake much closer... how do they distinguish and measure it?

[ElizabethMJJ]

This can't be true! Now i also watch you videos for fun! :D
You are THE BEST!

[Brian]

@Zanirtak i did as well

this is not something they taught me in school... very interesting