a summary of the physical and chemical nature of life must begin, not on the earth, but in the sun; in fact, at the sun"s very center. it is here that is to be found the source of the energy that the sun constantly pours out into space as light and heat. this energy is librated at the center of the sun as billions upon billions of nuclei of hydrogen atoms collide with each other and fuse together to form nuclei of helium, and in doing so, release some of the energy that is stored in the nuclei of atoms. the output of light and heat of the sun requires that some 600 million tons of hydrogen be converted into helium in the sun every second. this the sun has been doing for several thousands of millions of year. the nuclear energy is released at the sun"s center as high-energy gamma radiation, a form of electromagnetic radiation like light and radio waves, only of very much shorter wavelength. this gamma radiation is absorbed by atoms inside the sun to be reemitted at slightly longer wavelengths. this radiation , in its turn is absorbed and reemitted. as the energy filters through the layers of the solar interior, it passes through the x-ray part of the spectrum eventually becoming light. at this stage, it has reached what we call the solar surface, and can escape into space without being absorbed further by solar atoms. a very small fraction of the sun"s light and heat is emitted in such directions that after passing unhindered through interplanetary space, it hits the earth.
能源(The source of Energy)
- 相關文章
- 用新課程理念充實國小英語課堂_英語教學論文,用新課程理念充實小
- 英語完形填空題應試策略_英語教學論文,英語完形填空題應試策略_
- 淺析在英語教學中如何培養學生創新能力_英語教學論文,淺析在英語
- 中學英語教學改革二十年之回顧_英語教學論文,中學英語教學改革二
- 淺談定語從句_英語教學論文,淺談定語從句_英語教學論文範文
- 活化課堂的幾種手段_英語教學論文,活化課堂的幾種手段_英語教學
- 備課中的幾個問題──從中學英語教學實習談起_英語教學論文,備課
- 關于建立高中英語會考標準參照系統和分數報告系統的思考_英語教
- 高中英語課外閱讀教學的實踐_英語教學論文,高中英語課外閱讀教學
- 從NMET的閱讀題型談閱讀能力的培養_英語教學論文,從NMET的閱讀題
- 情態 動詞進行/完成進行時_英語教學論文,情態 動詞進行/完成進行
- CET4指南:完形填空的測試形式_英語教學論文,CET4指南:完形填空
- 直接引語變間接引語面面觀_英語教學論文,直接引語變間接引語面面
- 平衡看待雙語優勢_英語教學論文,平衡看待雙語優勢_英語教學論文
- 2000年黑龍江省高中畢業會考英語試卷評析_英語教學論文,2000年黑
- NMET2002書面表達錯誤分析及應試對策_英語教學論文,NMET2002書面
- 天津英語會考標準_英語教學論文,天津英語會考標準_英語教學論文
- 2004年考研英語作文講評_英語教學論文,2004年考研英語作文講評_
- 英語教學活動中作業布置法的實踐與研究_英語教學論文,英語教學活
- How to improve the ability of list