22/23 第一期天文冷知識：哈勃：起源

(The English version follows the Chinese one)

唔知大家喺啱啱嘅聖誕節有冇收到禮物呢？🎄🎁有嘅話恭喜晒，冇嘅都唔緊要，NASA今年聖誕送咗一份大禮畀我哋咁多位天文愛好者！.詹姆斯．韋伯太空望遠鏡（James Webb Space Telescope）喺2021年12月25號夜晚8點20分（香港時間）成功升空喇！ 🎊🎉🎉.James Webb其實係已經31歲嘅哈勃太空望遠鏡（Hubble Space Telescope）嘅細佬嚟㗎，相信唔少人都聽過Hubble嘅大名，網上搵到大多數天文嘅相都係出自Hubble㗎！等我哋一齊回顧下Hubble嘅起源啦！😌😌

_____Hubble係邊個？🤔🤔

Hubble係以一個美國嘅天文學家愛德溫．哈勃（Edwin Hubble）（圖一）命名嘅天文望遠鏡。根據愛因斯坦嘅廣義相對論，佢計算到宇宙居然會膨脹，當時大部分嘅天文學家都唔相信。因此，愛因斯坦修改計算嘅公式，令到結果符合返當時嘅宇宙觀🤏🏻👌🏻.然而，幾年之後哈勃用一支200吋口徑嘅望遠鏡發現原來除咗銀河系以外，仲有其它星系嘅存在，更加發現離我哋越遠嘅星系，會以越快嘅速度離開我哋添🏃‍♀️🏃哈勃呢一項觀察證明咗宇宙的而且確係會膨脹，亦都為宇宙大爆炸理論提供咗有力嘅證據，最尾令哈勃被譽為「星系天文學之父」👨‍👧‍👦👨‍👧‍👦Hubble影咗咁多唔同星系嘅相，令我哋大大加深咗對星系嘅認識，以呢位咁有份量嘅天文學家命名真係實至名歸呀！

_____點解要有Hubble？

明明我哋喺地面已經有唔少超大嘅望遠鏡，點解要特登發射一支相對地細嘅上太空呢？噉係因為地面嘅望遠鏡同星星之間有一層大氣層隔住，空氣不停嘅晃動會影響我哋影出嚟嘅效果。呢個亦解釋到點解我哋望到星星嘅時候會閃吓閃吓噉✨✨.除此之外，大氣層會吸收大部分嘅紅外線🔴同紫外線🟣，令我哋睇少咗好多嘢，不過用太空望遠鏡就可以解決呢個問題喇！

_____Hubble升空重重困難？

Hubble升空經歷咗一番嘅波折，原定喺1983年升空，可惜因為技術同金錢嘅問題😞同埋當時載有7個太空人嘅挑戰者號升空1分鐘後就解咗體😔令到大家都唔敢再喺短時間内繼續任何計劃😫😖而喺1990年，Hubble終於升空喇😝😝😝但結果上到去先發現個主鏡有問題⚠️⁉️又用多3年整返好佢，最終Hubble喺1993年可以為我哋服務喇！😎😎

_____Hubble「壽終正寢」？

足足過咗31年之後，Hubble終於有接班人喇！唔通佢嘅使命噉就結束？其實佢預計仲要做多10－20年㗎👵👴，例如繼續影吓離我哋好遠嘅星系，不過新嘢都係交返畀James Webb做啦~~~ 💁‍♀️💁.James Webb仲可以睇到啲咩？James Webb除咗會幫我哋影多啲靚相之外，究竟佢仲會點樣協助天文學家更深一層噉理解呢個宇宙呢？佢同Hubble又有咩分別呢？想知嘅話就千祈唔好錯過嚟緊由朱明中教授演講嘅《太空巨眼－詹姆斯·韋伯太空望遠鏡可以看見甚麼？》喇！📢📢📢講座將會喺3月3號夜晚7點鐘喺Zoom舉行（詳情可以參閱講座嘅IG post），真係等到我頸都長埋啊！💨🤥到時記得準時到喇！⌚️⏰

Hubble: The Origin

Did you receive any presents last Christmas? If yes, congratulations! If not, no worries, the National Aeronautics and Space Administration (NASA) has given us the greatest present ever. The James Webb Space Telescope (JWST) has been successfully launched at 20:20 (HKT) on 25 December 2021!.JWST is the younger brother of the Hubble Space Telescope (HST), which is already 31 years old! Most of you may have heard of this name for a long time. Loads of photos of planets and galaxies found online are all taken by HST! Let’s take a look at the origin of the HST!

_____Who is Hubble?

HST was named after the famous American astronomer Edwin Hubble (Figure 1). In the early 1900s, Einstein estimated the existence of the Universe expansion from his general theory of relativity while most astronomers did not believe in this thought, including Einstein himself. In order to prevent the above solecism, Einstein, therefore, revised the calculation method to prove that the Universe remains unchanged at all times..Nevertheless, a few years later, Hubble used a 200-inch telescope to discover that not only are those galaxies receding from our Milky Way, but the further they are, the faster they are receding. Based on the discovery of Hubble, there is no doubt that the Universe is expanding and he also proved the “Big Bang” theory with solid evidence. Eventually, Hubble was lauded as the father of modern cosmology. Pictures of different galaxies taken by HST has substantially strengthened our knowledge of the galaxies. Hubble’s reputation as an astronomer is truly well-deserved!.Why is HST needed?

If there are already so many huge telescopes on the Earth, why is there a need for delivering a relatively smaller telescope to space? As there is an atmosphere between the stars and the telescopes on the surface, some serious atmospheric disturbance will occur and hence, affect the quality of images taken. This also explains why stars twinkle from our naked eyes..Furthermore, the absorption of both infrared and ultraviolet light from the atmosphere blocks us from viewing more detail from outer space. By sending telescopes out of the atmosphere, these problems can be solved.

_____Difficulties in launching HST?

NASA encountered lots of problems when it tried to launch HST into space. HST was supposed to be launched in 1983. Concerning technical and financial issues, a space shuttle called the Challenger broke apart 1 minute after launching, unfortunately killing all 7 members inside the shuttle. Due to this tragedy, they are unwilling to perform another launch in the next few years..In 1990, HST was finally launched and reached its destination after several attempts. However, they discovered that the main mirror was still flawed, and it took 3 additional years to fix it. In 1993, HST was fully operational ultimately..Has HST finally come to an end?

After 31 years, HST finally has a successor! HST hasn’t come to an end and it is planned to work for 10-20 years more from now onwards. For instance, HST will still be taking pictures of distant galaxies. Let’s wait for JWST to take over the new missions!

_____What may we see with JWST?

Apart from taking more astonishing pictures, how may JWST help astronomers learn more about the universe? What are the differences between HST and JWST? Want to know more about JWST? Come join us in the upcoming talk “James Webb Space Telescope – What may we see?” held by Professor CHU Ming Chung next week!.You will not want to miss this valuable chance! The talk will be held on 3 March 2022 (Thurs), 19:00 on Zoom. Further information can be found in our previous post. Can’t wait to see you all there!