Before Cassini, scientists viewed Saturn’s unique features only from Earth and from three spacecraft flying by. During more than a decade orbiting the gas giant, Cassini studied the planet from its interior to the top of the atmosphere. It observed the changing seasons, provided up-close observations of Saturn’s exotic storms and jet streams, and heard Saturn’s lightning, which cannot be detected from Earth. During the Grand Finale orbits, it dove through the gap between the planet and its rings and gathered valuable data on Saturn’s interior structure and rotation. Key discoveries and events include: watching the eruption of a planet-encircling storm, which is a 20- or 30-year event, detection of gravity perturbations from winds 9000 km below the tops of the clouds, demonstration that eddies are supplying energy to the zonal jets, which are remarkably steady over the 25-year interval since the Voyager encounters, re-discovery of the north polar hexagon after 25 years, determination of elemental abundance ratios He/H, C/H, N/H, P/H, and As/H, which are clues to planet formation and evolution, characterization of the semiannual oscillation of the equatorial stratosphere, documentation of the mysteriously high temperatures of the thermosphere outside the auroral zone, and seeing the strange intermittency of lightning, which typically ceases to exist on the planet between outbursts every 1–2 years. These results and results from the Jupiter flyby are all discussed in this review.

中文翻译：

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卡西尼号土星探索：全面回顾


在卡西尼号之前，科学家只能从地球和飞过的三艘航天器上观察土星的独特特征。在围绕这颗气态巨行星运行的十多年里，卡西尼号对这颗行星进行了从内部到大气层顶部的研究。它观察了季节的变化，近距离观察了土星奇异的风暴和急流，并听到了地球上无法探测到的土星闪电。在最终轨道上，它穿过土星与其光环之间的间隙，收集有关土星内部结构和自转的宝贵数据。主要发现和事件包括：观察环绕行星的风暴的爆发（这是一个 20 或 30 年的事件）、探测云顶以下 9000 公里处风的重力扰动、证明涡流正在为地球提供能量。纬向急流，自航行者号遭遇以来的 25 年间隔内非常稳定，25 年后重新发现北极六边形，确定元素丰度比 He/H、C/H、N/H、P/H 、和 As/H，它们是行星形成和演化的线索、赤道平流层半年振荡的特征、极光区外热层神秘高温的记录，以及看到闪电的奇怪间歇性（通常会停止）每 1-2 年就会在地球上存在一次爆发。这些结果和木星飞越的结果都在这篇评论中进行了讨论。