Schematic illustration of Earth's magnetic field.
集思廣益：太陽可以從西方昇起！
作者：大異人
集思廣益：面對一個問題，每個人自己所能思考的範圍有限，如果集合一群人共同思維， Brain Storming的結果可開展大家的知見，共享成果。
在八月份主題「如果」中，市長舉例提出的「如果太陽從西方昇起？」在詩人心底可能浮起無盡的浪漫情懷；但在科學家眼裡則為一「大哉問」！
大異人的科學「常識」還算豐富，但出自主觀意識的「死腦筋」只冒出來一個意念：讓月球誕生的行星撞擊，都不能使地球的地軸反著轉，如果力量大到使地軸反著轉，地表的動、植、一切生物必遭大滅絕…….. 那麼，大家就得去到天堂或極樂世界再見了！
幸好科學訓練的直覺就是「此乃獨夫之見」，必須「集思」；反射動作則是為文「提出問題及己見，以拋磚引玉」。
果不其然，寶玉紛至！請看：
第一類：方向是人訂的
如果~~地球反著轉 http://blog.udn.com/jfeng13x/108381453
1樓. 深思者 2017/08/17 11:27
方向是人訂的，怎麼轉，只是雨下的地方不一樣。
回覆：
果然是深思者！把東和西的定義反調一下就成了！不過地球還是玩它自己的，哈哈哈。
如果~~東方朔說：太陽從北方昇起！你相信嗎？ http://blog.udn.com/jfeng13x/108378349
1樓. 文武兩邊站, 可可疊羅漢 2017/08/16 09:02
所謂的東南西北的方位，既然是人訂的，如果有人以不同的名稱定義這些方位，那麼太陽從「北方」升起也不能說不對。反正再怎麼便，太陽還是會從原本的方位升起降落。
好比這「指鹿為馬」，如果不看歷史故事，若某人從小就被教導這種動物的名稱是馬，那麼他長大後便也認定該動物是馬，不會是鹿。
回覆：
正如君言！閣主即為自幼被「日出東方」洗腦者，中年方「後知後覺」地「悟道」，哈哈哈…………
本文旨在提供週三娛樂，不在「懸疑」，故不再賣關子，請看：太陽從北方昇起 http://blog.udn.com/jfeng13x/81415509
一把尺 http://blog.udn.com/jfeng13x/81291892
2樓. 瞎摸 (或?) 著象 2017/08/18 10:57
哦 ? !
世上 常有 完全相反的理論﹐ 都對。 例如﹐乘噴射客機﹐妳說往東﹐他說往西﹐豈不是180° 完全相反, 可 都能到達 美國 (殊途同歸﹐〝條條大路通羅馬〞)。 哈﹐地球是圓的 ? http://classic-blog.udn.com/mbr8879576/267010
宇宙 或 也是圓的 ? (艾因斯坦: 光綫会因重力弯曲)
第二類：地球磁極反轉
Lansing 2017/08/18：「如果….」--拉拉手吧？ http://blog.udn.com/genglansing/105162362
87F回覆之回覆：
Sunrise in the WEST： Scientists warn North could be South as Earth’s magnetic poles switch. （註：本引用文網址因鎖右鍵，不能複製，請自行往閱上附網址。）
附錄另一網址供參考：
NASA 2012: Magnetic Pole Reversal Happens All The (Geologic) Time https://www.nasa.gov/topics/earth/features/2012-poleReversal.html
Credits: Peter Reid, The University of Edinburgh
Scientists understand that Earth's magnetic field has flipped its polarity many times over the millennia. In other words, if you were alive about 800,000 years ago, and facing what we call north with a magnetic compass in your hand, the needle would point to 'south.' This is because a magnetic compass is calibrated based on Earth's poles. The N-S markings of a compass would be 180 degrees wrong if the polarity of today's magnetic field were reversed. Many doomsday theorists have tried to take this natural geological occurrence and suggest it could lead to Earth's destruction. But would there be any dramatic effects? The answer, from the geologic and fossil records we have from hundreds of past magnetic polarity reversals, seems to be 'no.'
Reversals are the rule, not the exception. Earth has settled in the last 20 million years into a pattern of a pole reversal about every 200,000 to 300,000 years, although it has been more than twice that long since the last reversal. A reversal happens over hundreds or thousands of years, and it is not exactly a clean back flip. Magnetic fields morph and push and pull at one another, with multiple poles emerging at odd latitudes throughout the process. Scientists estimate reversals have happened at least hundreds of times over the past three billion years. And while reversals have happened more frequently in "recent" years, when dinosaurs walked Earth a reversal was more likely to happen only about every one million years.
簡言之，地球磁極南北反轉是「常態」，故太陽從西方昇起也是「常態」。值得欣慰的是地球不滅，生物物種不滅~~參見前段紅字部分。
第三類：地球被撞而反著轉
參考文： Why does the Sun rise in the East and set in the West?
https://www.quora.com/Why-does-the-Sun-rise-in-the-East-and-set-in-the-West
Can it rise in the West though? Does it happen on any planets?
Yes it does! Venus（金星）and Uranus（天王星）spin from East to West, so the Sun rises in the West. They are the only two planets the spin the opposite way. They’re cool like that.
Oh! But why are they special?
We still haven’t figured that out yet. But there are some theories. Venus（金星） is thought to have been spinning like the rest of them in the beginning, but may have slowly switched direction due to the massive storms on it surface. Venus doesn’t even rotate that fast anyways. In fact, one Venus day (254 Earth days) is longer than one Venus year (224 Earth days).
When it comes to Uranus（天王星）, it’s spin is almost perpendicular to the way the rest of the planets spin. We suspect that something big has hit Uranus really hard on it’s head and ever since, Uranus has been rolling along on it’s path around the Sun.
………………………………………
簡言之，天王星的腦袋被一個「大東西」撞得反著轉。如果地球也遭此一劫，造成「地軸」反著轉，太陽故將從西方昇起，物種大滅絕也是必然結局。
第二類和第三類的不同之處：
第二類的「磁極反轉」只是地球上的「局部」變化，並不影響地軸旋轉，而產生如第三類的巨變。
Whoo!
「集思廣益」，「死腦筋」終於變活了些，哈哈哈…………
感謝好友們的回饋！
通常，要那拖著小碎步的馬兒「打大波」（galloping），非得在馬肚子上踢它一腳不可。所以特別感謝龍公主未使出龍爪功，僅僅一聲龍吟（註1）就催出了這份補考的答卷，哈哈哈…………
（註1）龍吟 http://blog.udn.com/jfeng13x/103337933
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