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Glorious New Saturn Image: JWST Has Now Captured All 4 Giant Planets
With the addition of Saturn, the James Webb Space Telescope has finally captured all four of our Solar System's giant worlds.
JWST's observations of the ringed planet, taken on 25 June 2023, have been cleaned up and processed, giving us a spectacular view of Saturn's glorious rings, shining golden in the darkness.
By contrast, the disk of Saturn is quite dark in the new image, lacking its characteristic bands of cloud, appearing a relatively featureless dim brown.
This is because of the wavelengths in which JWST sees the Universe – near- and mid-infrared. These wavelengths of light are usually invisible to the naked human eye, but they can reveal a lot.
For example, thermal emission – associated with heat – is dominated by infrared wavelengths. When you're trying to learn about what's going on inside a planet wrapped in thick, opaque clouds, studying its temperature is a valuable way to go about it.
Some elements and chemical processes emit infrared light, too. So seeing the planets of the Solar System in wavelengths outside the narrow range admitted by our vision can tell us a lot more about what they have going on.
Saturn
As we saw last week, when we clapped eyes on the raw JWST Saturn images, the observations involved filters that dimmed the light of the planet, while allowing light from the rings and moons to shine brightly. This is so a team led by planetary scientist Leigh Fletcher of the University of Leicester in the UK can study the rings and moons of Saturn in more detail.
They hope to identify new ring structures and, potentially, even new moons orbiting the gas giant. The image above shows three of Saturn's moons, Dione, Enceladus, and Tethys, to the left of the planet. Although dim, the disk of the planet also reveals information about Saturn's seasonal changes.
The northern hemisphere is reaching the end of its 7-year summer, but the polar region is dark. An unknown aerosol process could be responsible. Meanwhile, the atmosphere around the edges of the disk appears bright, which could be the result of methane fluorescence, or the glow of trihydrogen, or both. Further analysis could tell us which.
Jupiter
Jupiter was the first of the giant planets to get the JWST treatment, with images dropping in August of last year – and boy howdy were they stunning.
The spectacular detail seen in the planet's turbulent clouds and storms was perhaps not entirely surprising, but we also got treated to some rarely seen features: the permanent aurorae that shimmer at Jupiter's poles, invisible in optical wavelengths, and Jupiter's tenuous rings.
We also saw two of the planet's smaller, lesser-known moons, Amalthea and Adrastea, with fuzzy blobs of distant galaxies in the background.
"This one image sums up the science of our Jupiter system program, which studies the dynamics and chemistry of Jupiter itself, its rings, and its satellite system," said astronomer Thierry Fouchet of Paris Observatory in France, who co-led the observations.
Neptune
Observations of Neptune arrived in the latter half of September 2022. Because Neptune is so very far away, it tends to get a little neglected; you're probably used to seeing, if anything, the images taken by Voyager 2 when it flew past in 1989. JWST's observations gave us, for the first time in more than 30 years, a new look at the ice giant's dainty rings – and the first ever in infrared.
It also revealed seven of Neptune's 14 known moons, and bright spots in its atmosphere. Most of those are storm activity, but if you look closely, you'll see a bright band circling the planet's equator. This had never been seen before and could be, scientists say, a signature of Neptune's global atmospheric circulation.
Uranus
Uranus is also pretty far away, but it's also a huge weirdo. Although very similar to Neptune, the two planets are slightly different hues, which is something of a mystery, and Uranus is also tipped sideways, which is challenging to explain too.
JWST's observations, released in April 2023, aren't solving these conundrums, but they have revealed 11 of the 13 structures of the incredible Uranian ring system, and an unexplained atmospheric brightening over the planet's polar cap.
JWST has a lot to say about the early Universe; but it's opening up space science close to home, too. As its first year of operations comes to an end, we can't help but speculate what new wonders will be to come in the years ahead.
注释：
opaque: adj
表示" 不透明的；难懂的 "，means " not able to be seen through; hard to understand"，如：The window is made of opaque glass. 这扇窗是用不透明的玻璃做的。
clap: v
表示" 轻拍；鼓掌"，means "strike the palms of the hands together"，如：She clapped her hands in delight. 她高兴地拍手。
aerosol: n
表示"气溶胶 "，means "a cloud of solid or liquid particles in a gas"，如：Deodorants are available as aerosols or roll-ons. 除臭剂有喷雾装或滚抹装。
methane: n
表示" 甲烷；沼气 "，means "a colorless odorless gas used as a fuel", 如：Cattle release methane when they digest their food. 牛在消化食物时,会释放出甲烷。
fluorescence: n
表示" 发荧光；荧光 "，means "light emitted during absorption of radiation of some other (invisible) wavelength "，如：At one o'clock at night, Xiaozhang saw fluorescence in the cemetery. 小张半夜一点的时候在坟场看到了荧光。
trihydrogen：adj
表示" 三氢的"，如：potassium trihydrogen oxalate 草酸三氢钾
howdy: int.
表示"您好(招呼用语) "，means "an expression of greeting"
aurorae: n
表示"北极光 "，means "[ auroral ]的复数形式"，如：Scientists have mapped Mars's aurorae. 科学家绘制出了火星的极光。
tenuous: adj
表示" 脆弱的；稀薄的"，means "having thin consistency"，如：Our existence is far more tenuous than we might think. 但我们的生命远比想像得要脆弱。
fuzzy: adj
表示" 模糊的；毛茸茸的"，means "indistinct or hazy in outline; covering with fine light hairs"，如：His thinking was superficial and fuzzy. 他的想法肤浅又模糊。My hair is naturally wavy, so it gets fuzzy easily. 我的头发自然卷，所以容易毛茸茸的。
blob: n
表示" ；一滴"，means "an indistinct shapeless form"，如：Blobs of paint were dotted around the canvas. 油画布上满是涂抹的颜料。
Neptune: n
表示"海王；海王星 "，means " god of the sea; a giant planet with a ring of ice particles; the 8th planet from the sun is the most remote of the gas giants"，如：Neptune is the eighth planet of our solar system. 海王星是我们太阳系里的第八颗行星。
equator: n
表示" 赤道 "，如：The equator is an imaginary line. 赤道是一条实际上并不存在的线。
Uranus: n
表示" 天王星"，如：Uranus is only a tiny spot in the sky. 天王星只是天空中的一个极微小的点。
conundrum: n
表示" 谜语；难题"，means "a difficult problem"，如：I'm going to tell you why this conundrum exists. 我打算告诉你们为什么这个谜题存在。
Uranian: adj
表示"；天文学的；天王星的 "，如：Correlations of satellite positions and ring features occur in the Jovian, Uranian and Neptunian systems as well. 在木星、天王星、海王星的系统中，卫星的位置也和行星环的特性密切相关。
中文简要说明：
史上最昂贵的天文仪器-詹姆斯•韦伯太空望远镜(JWST)刚刚发布了土星的拍摄影像，终于完成了太阳系4大行星的特殊摄影，在红外线下的木星、土星、天王星海王星，呈现了与可见光波段完全不同的风格。
科学警报(ScienceAlert)报导，6月25日，NASA发布了韦伯望远镜的土星照片，经过处理后，我们发现土星光环非常耀眼，在黑暗中闪耀着金色的光芒；相比之下，土星本体却相当灰暗，也看不太出上头的云带。
这是因为韦伯望远镜观察宇宙的主要波长，是近红外线和中红外线。这些波长在肉眼上是看不见的，但它们却可以告诉我们很多事情。
以土星为例，它表现灰暗就知道它的云层之下没有多余的热源，而光环如此明显，则适合更详细地研究土星的环和卫星。
研究团队希望能够识别出新的土星环结构，甚至可能识别出其他未被发现的新卫星。
韦伯拍摄的木星也是一绝，在去年 8月发布了韦伯的木星照片时，科学家以「太令人惊叹」来形容。比如韦伯轻易的捕捉到木星两极的永久极光，以及木星脆弱1道光环。
韦伯在开机之后不久，海王星是它最早拍摄的目标之一，因为它是太阳系最远的行星，而科学家当时有些担心过亮的目标对韦伯不安全，然后韦伯也交出了出色的照片，是让我们 30 多年来，再一次对这个冰巨星有了新的认识，包括哈伯望远镜也难以见到的海王星光环，竟然就被韦伯完整的观察到。
它拍到海王星 14 颗已知卫星中的 7 颗，以及其大气层中的亮斑。其中大部分都是风暴活动，虽然它离太阳如此遥远，却有着强烈的大气环流。
天王星距离我们也很远，但它也是一个巨大的怪人。虽然体积与海王星非常相似，但两颗行星的色调略有不同。而且天王星是倾斜的，这也很难解释。
韦伯在 2023年4月发表了天王星照片，它拍摄到天王星环13道中的11个道，以及南北极冠上空，无法解释的大气增亮现象。虽然它没有解决历史难题，但这些新的研究课题则更为重要。
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