【天文】與 太陽 有關
淋完衫
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又要拋西瓜搵樓主
結合非常少嘅觀測數據，建立一個數學模型去解釋所得嘅觀測，係人類認識太陽(恆星)結構嘅方法
實有人話，未去過點肯定個模型一定岩？
其實無話一定岩，只係個模型恰到好處咁解釋到我地嘅觀測。所以如果你有更好又符合邏輯嘅理論，相信廣大嘅科學界會好欣賞同接納新嘅觀點
咁係你未有諗法之前，我地先睇下科學家點樣由零創造出黎
建設恆星模型嘅第一步，係提出假設，以減少需要考慮嘅因素。例如
假設太陽(主序星)係獨立唔受其他星體影響；
假設太陽(主序星)係唔旋轉而且球對稱 Spherically Symmetric，因為轉動嘅能量遠遠細於重力位能，所以可以忽略恆星嘅自轉；
假設均衡分佈嘅化學物質等等；
當中比較重要嘅係假設有兩個，第一個係 hydrostatic equilibrium 流體靜力平衡。
前面我地介紹過，科學家已經得知到太陽嘅某D物理性質，包括重量 Mass、半徑 Radius、溫度 Temperature以及亮度 Luminosity，而且知道佢地係互相連繫。
係人類持續嘅觀察下，發現太陽嘅呢D 特質係以極極極極極慢嘅速度改變緊
係人類嘅短暫歷史都唔會觀測到呢D特質嘅明顯嘅變化，細得幾乎可以忽略。
點樣先可以令一個人擁有嘅錢保持不變？好簡單，只要佢嘅收入同支出一樣就可以做到。
同樣原理，咁點樣可以令到太陽唔會變大變細，亦唔會變輕變重？
就係當太陽自己製造嘅能量所形成向外嘅壓力，同自身重量所形成向內嘅重力，剛好抵消，咁太陽就可以永恆不變
第二個係Local thermodynamic equilibrium 局部熱力學平衡。
簡單講係恆星內，足夠細嘅區域內嘅物理特性嘅差異都非常之少。
咁科學家就可以假設某個區域內嘅溫度、壓力都係處於相同水平，從而簡化模型。
咁經過科學家們嘅努力，一個恆星嘅結構，基本上就由呢幾條數學公式描述咗出黎。
過程中當然仲用咗好多其他嘅物理理論、數學公式，如果好多人想知我先再詳情，否則就skip
科學家加入太陽數據俾電腦進行運算，就得出標準太陽模型 Standard Solar Model，而認解到太陽內部嘅物理特質。.
例如右上角嘅密度圖，我地可以睇到，有～9成嘅太陽質量都係分佈於距離太陽核心0.5個半徑之內
下次繼續
屌你個名
見到樓主呢啲高質post真係好開心！
鍾意就好
點解地球圍住太陽轉一圈就365日
枝火箭走捷徑打直行太陽就要7年？
枝火箭走捷徑打直行太陽就要7年？
因為行星公轉速度真係快過火箭.
而且火箭燃料淨係用黎加速擺脫地球引力己經無左9成. 現行技術上無得再利用燃料加速.
而且火箭燃料淨係用黎加速擺脫地球引力己經無左9成. 現行技術上無得再利用燃料加速.
向地球前進方向發射會唔會令火箭有更快速度？
我知道幾十年來應該一早諗到
，有無得解下點解咁做唔會快啲，或者其實有用但去太陽都要七年？
我知道幾十年來應該一早諗到
，有無得解下點解咁做唔會快啲，或者其實有用但去太陽都要七年？非專業google關於地球公轉速度同火箭escape speed比較.
Earth's spin, of course, is not the only motion we have in space. Our orbital speed around the sun is about 67,000 mph (107,000 km/h), according to Cornell. We can calculate that with basic geometry.
https://www.space.com/33527-how-fast-is-earth-moving.html
Earth to solar escape 36,500 mph
With increasing speed it becomes harder and harder to gain another mile per hour. This is because the amount of fuel one has to carry becomes really big, and it becomes difficult and expensive to lift that much fuel into space. Solar escape velocity is nearing the practical limit of how fast one can move with conventional rockets.
http://www.qrg.northwestern.edu/projects/vss/docs/propulsion/2-how-fast-conventional.html
Earth's spin, of course, is not the only motion we have in space. Our orbital speed around the sun is about 67,000 mph (107,000 km/h), according to Cornell. We can calculate that with basic geometry.
https://www.space.com/33527-how-fast-is-earth-moving.html
Earth to solar escape 36,500 mph
With increasing speed it becomes harder and harder to gain another mile per hour. This is because the amount of fuel one has to carry becomes really big, and it becomes difficult and expensive to lift that much fuel into space. Solar escape velocity is nearing the practical limit of how fast one can move with conventional rockets.
http://www.qrg.northwestern.edu/projects/vss/docs/propulsion/2-how-fast-conventional.html
呢條問題, 不如等NASA直接答你.
Launch a rocket from a spinning planet
https://spaceplace.nasa.gov/launch-windows/en/
Launch a rocket from a spinning planet
https://spaceplace.nasa.gov/launch-windows/en/
同埋因為要預埋減速入orbit, SHORTCUT都唔係完全直線, 會flyby Venus.
Over the next two months, Parker Solar Probe will fly towards Venus, performing its first Venus gravity assist in early October – a maneuver a bit like a handbrake turn – that whips the spacecraft around the planet, using Venus’s gravity to trim the spacecraft’s orbit tighter around the Sun. This first flyby will place Parker Solar Probe in position in early November to fly as close as 15 million miles from the Sun – within the blazing solar atmosphere, known as the corona – closer than anything made by humanity has ever gone before.
http://parkersolarprobe.jhuapl.edu/News-Center/Show-Article.php?articleID=94
Over the next two months, Parker Solar Probe will fly towards Venus, performing its first Venus gravity assist in early October – a maneuver a bit like a handbrake turn – that whips the spacecraft around the planet, using Venus’s gravity to trim the spacecraft’s orbit tighter around the Sun. This first flyby will place Parker Solar Probe in position in early November to fly as close as 15 million miles from the Sun – within the blazing solar atmosphere, known as the corona – closer than anything made by humanity has ever gone before.
http://parkersolarprobe.jhuapl.edu/News-Center/Show-Article.php?articleID=94
LM
睇唔撚明, 唔好解釋D 數學野唔該
太複雜
?其實上面講左三點:
1) 人類無直接方法探測太陽內部,而要用數學理論去研究
2) 理論其中最重要嘅假設係太陽係永恆不變
3) 個理論叫Standard Solar Model
?其實上面講左三點:1) 人類無直接方法探測太陽內部,而要用數學理論去研究
2) 理論其中最重要嘅假設係太陽係永恆不變
3) 個理論叫Standard Solar Model
見到D公式就頭暈
向地球前進方向發射會唔會令火箭有更快速度？點解地球圍住太陽轉一圈就365日因為行星公轉速度真係快過火箭.
枝火箭走捷徑打直行太陽就要7年？
而且火箭燃料淨係用黎加速擺脫地球引力己經無左9成. 現行技術上無得再利用燃料加速.
我知道幾十年來應該一早諗到
係囉
你地球起飛唔係已經有個慣性係到？
利申 DSE PHY Level 3
光都要8分鐘啦
7年好快以啦
7年好快以啦