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Reading Comprehension - Worked Examples

Current time:0:00Total duration:7:23

Science passage overview | The Sun

Reading Comprehension - Worked Examples

Video transcript

here's a science passage from the reading comprehension section in this video as I markup the passage I mean it's paid special attention to words like but however yet and although because they're going to tell me that an important contrast is about to be discussed I'll also try to call out the most important claims and conclusions in the passage as well as the different points of view of the various people who are mentioned at the end of the video I'm going to sum up the entire passage and recap some of those annotation techniques and how they might help us as we approach the questions ok let's go in the early 1900's most astronomers are mistakenly believed that 66 percent of the sun's substance was iron ok so mistaken belief that 66 percent of the substance of the sudden substance was iron ok as a graduate student at Harvard University of the 1920s ok that's when we're talking about Cecilia Payne later a professor of astronomy there argued pioneering Lee that the Sun is instead composed largely of hydrogen and helium her claim though substantiated by the evidence and later uniformly accepted encountered strong resistance among professional astronomers so that's our introduction she has a claim that encountered strong resistance among professional astronomers so she had some trouble getting her ideas accepted the Orthodox view that the Sun was mainly ironed was buttressed by the knowledge that earth and all known asteroids contain iron also the evidence from spectroscopy what's that a technique used to identify chemicals by the distinctive spectral properties of the light patterns they emit when heated to incandescence Kennedy evidence from spectroscopy was generally taken to show that iron was the predominant element in the Sun ok so that evidence is making supporting the argument for higher but how could a body composed largely higher generate the huge energy output of the Sun because that's a big question that people are trying to answer the eminent British physicist Lord Kelvin had hypothesized that the Sun was continuously contracting and that the resulting compress had raised the temperature of the sun's materials sufficiently to account for its enormous heat solar Calvin had a theory there's the contraction and the compression then raise the temperature of the sun's materials to account for the heat okay but okay however given the usual assumptions about the sun's size and rate of contraction it followed that the sun's age would be about 20 million years evidence from the fossil record however however strongly suggested that the Sun had warmed earth for billions of years billions of years millions not so much the fossil record tells us that it was billions for painting this meant that the iron hypothesis had to be re-examined together with the extensive spectroscopic data alleged to support it so she didn't believe that I thought the iron hypothesis could possibly be right and so she wanted to look at the spectroscopic data again preliminary examination of the spectroscopic data convinced pain that they left themselves to multiple readings okay she's on - she's on a case she's found some evidence she suspected that preconceptions about the sun's makeup as being mainly iron might have led to skewed interpretations of that data and this led her to subject the data to rigorous critical scrutiny and review so she thinks that preconceptions led people to interpret it in a certain way analyzed without preconceptions she found the data could be consistently red indicating that while it does indeed contain iron okay there's some iron along with other elements found on earth 90% of the Sun is hydrogen and most of the remainder is helium okay so she is reinterpreting the data and it she thinks it's consistently telling us that it's hydrogen and helium not iron most astronomers at the time dismissed Payne's interpretation and some sought to explain it away simply by claiming that what she had examined was data about the sun's outer surface rather than its interior so most astronomers dismissed her interpretation they said you know if you have a mistake here you're probably looking at something else absent a generally accepted explanation of how hydrogen and helium could produce the sun's energy Payne's findings could not easily override her contemporaries preconceptions we now know now no it's not the twenty it anymore we now know that sun's heat sun's heat is generated through nuclear fusion the Sun's gravitational force compresses together atoms of hydrogen causing a nuclear reaction so the compression problem is real at that but is compressing the hydrogen which caused the nuclear reaction this reaction produces enormous amounts of energy while forming helium and other elements but there's another but but this process so well charted today that even elementary physics textbooks discuss it was inadequately understood in the 1920s the process wasn't understood in the 1920s the emergence of that understanding which relied on Einstein's equation governing the relationship between mass and energy eventually provided strong confirmation of paints results so Einstein's equation governing the relationship between mass and energy finally vindicated Payne and her results okay thanks Einstein okay so that's the passage and let's just see how we might be able to summon a passage up okay it helps to sum it up in your own words so that you really know you have control of what's going on in the passage Cecilia Payne took a close look at the spectroscopic data from the Sun and concluded that it showed that the Sun was made up mostly of hydrogen and helium there's a little bit of iron but mostly hydrogen helium the spectroscopic data supported this conclusion but because the process of nuclear fusion wasn't understood at the time no one could explain how a Sun made of hydrogen and helium could generate all that heat other scientists didn't believe it they were all convinced that the Sun was made of iron including Lord Kelvin whose theory was that the gravity of all that iron has got to be squeezing it so tightly that that alone that compression generates heat Turner Payne was finally vindicated when fusion was discovered nuclear fusion was discovered so basically the passages main point is that is about Payne theory and how it eventually came to be accepted now that this cottage is a really good example of competing scientific nerve sometimes it'll be a kind of a say I say situation in which the author makes an argument that conflicts with other people's theories and sometimes the author will showcase two or more competing theories about the same thing you also may find that the passage charts a chronological development of scientific consensus or maybe their lack of consensus in a certain area of scientific inquiry that's about it we've summed it up in our head and are ready to go to the questions let's do it