Cepheid variables 1 | Stars, black holes and galaxies | Cosmology & Astronomy | Khan Academy
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Cepheid Variables 1. Created by Sal Khan. Watch the next lesson: https://www.khanacademy.org/science/cosmology-and-astronomy/stellar-life-topic/cepheid-variables/v/why-cepheids-pulsate?utm_source=YT&utm_medium=Desc&utm_campaign=cosmologystronomy Missed the previous lesson? https://www.khanacademy.org/science/cosmology-and-astronomy/stellar-life-topic/stellar-parallax-tutorial/v/parsec-definition?utm_source=YT&utm_medium=Desc&utm_campaign=cosmologystronomy 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! About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content. For free. For everyone. Forever. #YouCanLearnAnything Subscribe to Khan Academy’s Cosmology & Astronomy channel: https://www.youtube.com/channel/UChNPnEkW8LYZ5Rwi8_A2-DA?sub_confirmation=1 Subscribe to Khan Academy: https://www.youtube.com/subscription_center?add_user=khanacademy
Comments
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Great explanation and video , thanks.
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Truly a great explanation, was very interesting
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It is the best explanation of how she figured it out, I have learned more in this video than all my books pn Astronomy,
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Sal, is there anything you don't know? LOL
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Khan, you are singlehandedly changing education around the world. Thanks for all you have done and keep up the good work
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Luminosity varies due to the makeup of the stars. If a star is massive and made up of mostly hydrogen, it will burn fast and hot. Other stars, like our sun, will live for billions of years but are much smaller. Still other stars are relatively tiny! Look around Wikipedia and other places to read about Main Sequence Stars.
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I have a GCSE physics exam, and although i have 100 percent in all the modulars, the last one has this topic and it is has baffled me until now, Thank you so much for this Really Helpful :)
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Using this video to study for exam.
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when they are small and hot, they are intense, but their brightness to the earth is lower since they are smaller, it eventually reaches a point where the brightness declines again during expansion (at point where coolness is affecting brightness more than size--heat decreasing faster than size is increasing-etc)
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the stars themselves are contracting and expanding, as they heat their light peaks as they are hot and expanding (somewhat large)--before cooling--and is lowest when they are around the same volume but cool and contracting
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that was awesome
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Great video. Thanks!
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@LogicBeforeNorms Nah, it wasn't Dianetics. I did try to read Dianetics once - I was hoodwinked into buying it by a friendly salesperson on the street when I was very gullible. What a crock it was. Just a bunch of made up pseoduscience IMHO. The galaxy book is pretty good though!
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@LAnonHubbard Lol... that book wasn't Dianetics was it?
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I was reading a book the other day called Galaxies: A Very Short Introduction. The explanation of Cepheid variables in there made sense mostly but I didn't connect all the dots. Watching this video has made me understand it properly now. Thanks!!
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wow amazing video
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What makes their luminosity vary?
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your a genius...! It's really cool that you have videos on all the sciences like Bio, chemistry,astronomy, and other stuff ... soooooooo sick !!!!
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It's always the little things.
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