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Photo credit: NASA, ESA, CSA, Northrop Grumman

In the vast realm of space, a revolutionary tool has been geared up to propel our exploration of the cosmos – the James Webb Space Telescope. Set up as a successor to the Hubble Space Telescope, Webb was launched in December 2021 with the aim of uncovering the formation of galaxies, stars, and planets [1]. As an extremely long duration is needed for the light from a very distant object to reach us, the observation we make today is actually reflecting their appearance in the past, providing us a peek into the early universe. Observing the conditions during the formation of the first galaxies enables scientists to trace the origins of our own galaxy, along with the planets and stars it encompasses.

Named after a prior administrator of NASA [2], Webb represents key advancements in the usage of space telescopes, and is the largest and most intricately designed observatories ever sent into space. The main component of the telescope, known as the primary mirror, functions to capture red and infrared light to facilitate the observation of far-off objects that are highly redshifted (footnote 1) [3, 4]. The mirror then reflects the light onto a smaller secondary mirror, where it is redirected to scientific instruments for interpretation.

A large primary mirror can reveal more details of a far-off object by collecting more light signals from it. Webb has a light collecting area 6.25 times greater than that of the Hubble Space Telescope [4], but one of the biggest challenges was the technical restriction of launching such a large mirror into space. To overcome this hurdle, the telescope was innovatively designed to be a folding telescope – much like origami – where the mirror would unfold once they had detached from the launch vehicle.

Webb is also an incredible feat of engineering that has the capability of adjusting its focus with very fine precision. The primary mirror is made up of 18 hexagonal segments of beryllium [3], whose position can be adjusted independently by the tiny mechanical motors called actuators behind each segment. Controlled by the team on the ground, adjustments as fine as about 1/10,000th of the width of a human hair can be made to produce focused, sharp images [5].

Designed to detect infrared light from distant sources, Webb itself requires extremely low temperatures in order not to interfere with those faint heat signals. To shield the telescope from heat and light from external sources such as the Sun, Earth, and Moon, scientists designed a five-layered sunshield as large as a tennis court to allow the telescope to work at extremely cool temperatures below -220°C by passively deflecting heat from between the sunshield layers [6].

Since its launch in 2021, Webb has not only provided us with an array of findings and breathtaking images, but also context to the images captured previously by Hubble. One such image was that of the Pillars of Creation, captured in the Eagle Nebula (Figure 1). While Hubble had captured the brown clouds of the structure, Webb was able to leverage its infrared imaging to capture also the individual new stars forming within it [7].

Figure 1 Hubble telescope (left) vs. James Webb Space Telescope (right) on the Pillars of Creation [7].
Photo credit: NASA, ESA, CSA, STScI; Joseph DePasquale (STScI), Anton M. Koekemoer (STScI), Alyssa Pagan (STScI)

In addition, Webb was able to capture images of the most distant galaxies known to scientists [8]. There were also data that shed light on the collision of galaxies (Figure 2) [9], and the atmospheres of planets inside and outside our solar system [10-12].

Figure 2 NGC 3526, the spiral galaxy shown in this image as the wreckage of a collision between two similarly massive galaxies occurred around 500 million years ago [13].
Photo credit: ESA/Webb, NASA & CSA, L. Armus, A. Evans

The James Webb Space Telescope marks a historic leap in humans’ quest to understand the universe. Its innovative design and cutting-edge technology make it an ideal tool to revolutionize our comprehension of the cosmos. Keep up with the latest discoveries by the James Webb Space Telescope – one of the greatest scientific feats of today’s day and age!

Webb Gallery: A Collection of Stunning Images!

The Cosmic Cliffs. The image depicts the edge of a star-forming cavity within a cluster, called NGC 3324, located in the Carina Nebula. The ultraviolet radiation and intense winds from the young stars in the center of the cavity carve the area into what is called the “Cosmic Cliffs” [15, 16].

Photo credit: NASA, ESA, CSA, STScI

The Ring Nebula. A dying star which previously expelled its outer layers in concentric circles now ionizes and heats up its ejected gas to form this colorful ring-shaped planetary nebula. The bright ring is mainly composed of molecular hydrogen gas [17, 18].

Photo credit: ESA/Webb, NASA, CSA, M. Barlow (University College London), N. Cox (ACRI-ST), R. Wesson (Cardiff University)

Uranus and its moons. The larger image depicts the planet Uranus along with 14 of its 27 moons, and some distant background galaxies. The close-up shows Uranus and its rings in great detail, surrounded by nine of its moons [19, 20].

Photo credit: NASA, ESA, CSA, STScI

References 參考資料：

1. Kalirai, J. (2018). Scientific discovery with the James Webb Space Telescope. Contemporary Physics, 59(3), 251-290.
   https://doi.org/10.1080/00107514.2018.1467648
   https://www.tandfonline.com/action/showCitFormats?doi=10.1080/00107514.2018.1467648
2. Witze, A. (2022, November 21). NASA really, really won’t rename Webb telescope despite community pushback. Nature. https://www.nature.com/articles/d41586-022-03787-1
3. NASA. (n.d.). Webb’s Mirror. James Webb Space Telescope. https://webb.nasa.gov/content/observatory/ote/mirrors/index.html
4. NASA. (n.d.). Webb vs Hubble Telescope. James Webb Space Telescope. https://webb.nasa.gov/content/about/comparisonWebbVsHubble.html
5. Fisher, A. (2022, January 13). Mirror, Mirror…On Its Way! NASA Blogs. https://blogs.nasa.gov/webb/2022/01/13/mirror-mirroron-its-way/
6. NASA. (n.d.). The Sunshield Webb. James Webb Space Telescope. https://webb.nasa.gov/content/observatory/sunshield.html
7. NASA Webb Telescope Team. (2022, October 19). NASA’s Webb Takes Star-Filled Portrait of Pillars of Creation. NASA. https://www.nasa.gov/universe/nasas-webb-takes-star-filled-portrait-of-pillars-of-creation/
8. Cooper, K. (2023, November 14). James Webb Space Telescope finds 2 of the most distant galaxies ever seen. Space.com. https://www.space.com/james-webb-space-telescope-distant-galaxies
9. Lea, R. (2023, July 5). James Webb Space Telescope spots the wreckage of a cosmic clash of the Titans (image). Space.com. https://www.space.com/webb-telescope-galactic-collision-image
10. Sanders, R. (2023, July 27). James Webb Space Telescope sees Jupiter moons in a new light. Berkeley News. https://news.berkeley.edu/2023/07/27/james-webb-space-telescope-sees-jupiter-moons-in-a-new-light
11. Cable News Network. (2023, December 20). Uranus’ mysterious features on display in new Webb image. CBS News. https://www.cbsnews.com/baltimore/news/uranus-mysterious-features-on-display-in-new-webb-image/
12. NASA. (n.d.). Other Worlds. James Webb Space Telescope. https://webb.nasa.gov/content/science/origins.html
13. European Space Agency. (2023, July 3). Clash of the Titans. ESA/Webb. https://esawebb.org/images/potm2306a/
14. Schilling, G. (2023, February 8). Why galaxies look redder the further away they are. BBC Sky at Night Magazine. https://www.skyatnightmagazine.com/space-science/galaxies-redshift
15. NASA Webb Telescope Team. (2022, July 12). NASA’s Webb Reveals Cosmic Cliffs, Glittering Landscape of Star Birth. NASA. https://www.nasa.gov/image-article/nasas-webb-reveals-cosmic-cliffs-glittering-landscape-of-star-birth/
16. Space Telescope Science Institute. (2022, July 12). “Cosmic Cliffs” in the Carina Nebula (NIRCam Image). Webb Space Telescope. https://webbtelescope.org/contents/media/images/2022/031/01G77PKB8NKR7S8Z6HBXMYATGJ
17. Cesari, T. (2023, August 21). Webb Reveals Intricate Details in the Remains of a Dying Star. NASA Blogs. https://blogs.nasa.gov/webb/2023/08/21/webb-reveals-intricate-details-in-the-remains-of-a-dying-star/
18. Space Telescope Science Institute. (2023, August 21). Ring Nebula (NIRCam Image). Webb Space Telescope. https://webbtelescope.org/contents/media/images/01H82G0PP38P6PBXQ11BEVSMY0
19. Space Telescope Science Institute. (2023, December 18). Webb Space Telescope. https://webbtelescope.org/contents/media/images/2023/150/01HHFPR4A292D6X984CZ5QWD7J?page=3&filterUUID=91dfa083-c258-4f9f-bef1-8f40c26f4c97
20. Space Telescope Science Institute. (2023, December 18). Uranus Close-up (NIRCam image). Webb Space Telescope. https://webbtelescope.org/contents/media/images/2023/150/01HHFNNWQTA69J6K680PVZN4A1?news=true

Authors:
Roshni Printer

December 2024

图片来源：NASA, ESA, CSA, Northrop Grumman

在浩瀚无垠的太空中，一件革命性的工具已经悄然准备好推动我们对宇宙的探索 — 詹姆斯．韦伯太空望远镜（James Webb Space Telescope）。作为哈勃太空望远镜（Hubble Space Telescope）的继任者，韦伯望远镜于2021年12月升空，旨在揭示星系、恒星和行星形成的秘密 [1]。由于从极远距离物体发出的光需要极长的时间才能到达我们所在的位置，因此我们今天观察到的实际上是过去的景象，这为我们提供了一个窥探早期宇宙的机会。观察早期星系形成的环境有助科学家追溯我们星系，以及它所包含行星和恒星的起源。

韦伯望远镜以前美国太空总署（NASA）署长命名 [2]，它代表了人类在使用太空望远镜方面的重大发展，亦有史以来发射到太空最大和设计最复杂的观测仪器。望远镜的主要组件是主镜，用于捕捉红色可见光和红外线，这有利于观察高度红移的远距离物体（注）[3, 4]。主镜会将光线反射到较小的副镜上，然后再反射到仪器进行分析。

一块大面积的主镜可以透过从远距离物体收集更多光信号以提供更细致的影像。韦伯望远镜的主镜面积比哈勃望远镜大6.25倍 [4]，但随之而来的技术难题是怎样把如此巨大的镜子送上太空。为了克服这个障碍，技术人员活用创意，将望远镜像折纸一样，设计为一个可折叠的结构，当中镜子只会在望远镜脱离运载火箭后展开。

韦伯望远镜亦是工程技术上一项非凡杰作，皆因它拥有非常精密的对焦能力。主镜由18块以铍元素制成的六边形镜片组成 [3]，每块镜片背后都有称为致动器的微小的机械马达，可以独立微调镜片位置。地面团队可以透过对镜片进行微细至头发宽度10,000分一的精细调整，来对焦并产生清晰影像 [5]。

由于韦伯望远镜在设计上是用于侦测遥远物体发出的红外线信号，因此它需要维持极低的运作温度，才能避免自身的热干扰外来微弱的热信号。为了使望远镜能隔绝来自太阳、地球和月球等外来的热和光，科学家设计了一个网球场大小的五层遮光罩，使热力被动地从遮光罩各层之间反射离开，使望远镜能在低于零下220°C下运作 [6]。

自2021年发射以来，韦伯望远镜不仅为我们带来一系列的发现和令人惊叹的影像，还为哈勃望远镜之前拍摄的影像提供了更深入的资讯。其中一个例子是拍摄在鹰星云内的「创生之柱」（Pillars of Creation）（图一），尽管哈勃望远镜已经捕捉到了当中的棕色云，但韦伯望远镜利用其红外线成像技术，捕捉到当中正在形成的新恒星 [7]。

图一 ：由哈勃望远镜（左）及詹姆斯．韦伯太空望远镜（右）所拍摄的「创生之柱」[7]。
相片来源：NASA, ESA, CSA, STScI; Joseph DePasquale (STScI), Anton M. Koekemoer (STScI), Alyssa Pagan (STScI)

此外，韦伯望远镜不仅能拍摄科学家已知最遥远的星系 [8]，还收集了一些数据解释星系之间发生的碰撞（图二）[9]，以及让我们了解太阳系内外行星的大气层 [10-12]。

图二：NGC 3526 — 图中的螺旋星系为大约五亿年前两个质量相近星系碰撞后的残骸 [13]。
相片來源：ESA/Webb, NASA & CSA, L. Armus, A. Evans

詹姆斯．韦伯太空望远镜标志著人类探索宇宙的一大进程，其创新设计和尖端技术使其成为一件理想的工具去加深我们对宇宙的认识。就让我们继续关注韦伯太空望远镜的最新动向，紧贴现今科技的最前线！

韦伯相簿：一系列令人惊叹的相片！

「宇宙悬崖」（The Cosmic Cliffs） 图中展示位于船底座星云中一个名为NGC 3324的星团内部，一个正在孕育恒星的空腔的边缘。空腔中间由年轻恒星散发的紫外辐射和强风掏空了该区域，形成了图中的「宇宙悬崖」 [15, 16]。

相片来源：NASA, ESA, CSA, STScI

环状星云 垂死的恒星喷出同心圆状的外层，在使其离子化和加热后，这些喷出的气体形成色彩缤纷呈环状的行星状星云。图中明亮的环主要由氢气组成 [17, 18]。

相片来源：ESA/Webb, NASA, CSA, M. Barlow (University College London), N. Cox (ACRI-ST), R. Wesson (Cardiff University)

天王星及其卫星 大图显示天王星及其27颗卫星中的14颗，还有一些遥远的背景星系。特写细致展示了天王星和它的环，周围还有九颗卫星 [19, 20]。

相片来源：NASA, ESA, CSA, STScI

参考资料：

1. Kalirai, J. (2018). Scientific discovery with the James Webb Space Telescope. Contemporary Physics, 59(3), 251-290.
   https://doi.org/10.1080/00107514.2018.1467648
   https://www.tandfonline.com/action/showCitFormats?doi=10.1080/00107514.2018.1467648
2. Witze, A. (2022, November 21). NASA really, really won’t rename Webb telescope despite community pushback. Nature. https://www.nature.com/articles/d41586-022-03787-1
3. NASA. (n.d.). Webb’s Mirror. James Webb Space Telescope. https://webb.nasa.gov/content/observatory/ote/mirrors/index.html
4. NASA. (n.d.). Webb vs Hubble Telescope. James Webb Space Telescope. https://webb.nasa.gov/content/about/comparisonWebbVsHubble.html
5. Fisher, A. (2022, January 13). Mirror, Mirror…On Its Way! NASA Blogs. https://blogs.nasa.gov/webb/2022/01/13/mirror-mirroron-its-way/
6. NASA. (n.d.). The Sunshield Webb. James Webb Space Telescope. https://webb.nasa.gov/content/observatory/sunshield.html
7. NASA Webb Telescope Team. (2022, October 19). NASA’s Webb Takes Star-Filled Portrait of Pillars of Creation. NASA. https://www.nasa.gov/universe/nasas-webb-takes-star-filled-portrait-of-pillars-of-creation/
8. Cooper, K. (2023, November 14). James Webb Space Telescope finds 2 of the most distant galaxies ever seen. Space.com. https://www.space.com/james-webb-space-telescope-distant-galaxies
9. Lea, R. (2023, July 5). James Webb Space Telescope spots the wreckage of a cosmic clash of the Titans (image). Space.com. https://www.space.com/webb-telescope-galactic-collision-image
10. Sanders, R. (2023, July 27). James Webb Space Telescope sees Jupiter moons in a new light. Berkeley News. https://news.berkeley.edu/2023/07/27/james-webb-space-telescope-sees-jupiter-moons-in-a-new-light
11. Cable News Network. (2023, December 20). Uranus’ mysterious features on display in new Webb image. CBS News. https://www.cbsnews.com/baltimore/news/uranus-mysterious-features-on-display-in-new-webb-image/
12. NASA. (n.d.). Other Worlds. James Webb Space Telescope. https://webb.nasa.gov/content/science/origins.html
13. European Space Agency. (2023, July 3). Clash of the Titans. ESA/Webb. https://esawebb.org/images/potm2306a/
14. Schilling, G. (2023, February 8). Why galaxies look redder the further away they are. BBC Sky at Night Magazine. https://www.skyatnightmagazine.com/space-science/galaxies-redshift
15. NASA Webb Telescope Team. (2022, July 12). NASA’s Webb Reveals Cosmic Cliffs, Glittering Landscape of Star Birth. NASA. https://www.nasa.gov/image-article/nasas-webb-reveals-cosmic-cliffs-glittering-landscape-of-star-birth/
16. Space Telescope Science Institute. (2022, July 12). “Cosmic Cliffs” in the Carina Nebula (NIRCam Image). Webb Space Telescope. https://webbtelescope.org/contents/media/images/2022/031/01G77PKB8NKR7S8Z6HBXMYATGJ
17. Cesari, T. (2023, August 21). Webb Reveals Intricate Details in the Remains of a Dying Star. NASA Blogs. https://blogs.nasa.gov/webb/2023/08/21/webb-reveals-intricate-details-in-the-remains-of-a-dying-star/
18. Space Telescope Science Institute. (2023, August 21). Ring Nebula (NIRCam Image). Webb Space Telescope. https://webbtelescope.org/contents/media/images/01H82G0PP38P6PBXQ11BEVSMY0
19. Space Telescope Science Institute. (2023, December 18). Webb Space Telescope. https://webbtelescope.org/contents/media/images/2023/150/01HHFPR4A292D6X984CZ5QWD7J?page=3&filterUUID=91dfa083-c258-4f9f-bef1-8f40c26f4c97
20. Space Telescope Science Institute. (2023, December 18). Uranus Close-up (NIRCam image). Webb Space Telescope. https://webbtelescope.org/contents/media/images/2023/150/01HHFNNWQTA69J6K680PVZN4A1?news=true

作者：
Roshni Printer

2024年12月