This is an academic field that seeks to understand the characteristics of the many planets and moons in the solar system in a unified way. Data from planetary probes is being added to data from ground-based telescope observations, and it is making rapid progress. There are various approaches, such as observing terrestrial planets to gain a better understanding of the Earth, or linking it to the origin of the solar system and the origin of life. The oldest discussion has been about calculating the average density from the (apparent) mass and radius obtained from observations, and trying to grasp the general structure of the planet's body by comparing it with metallic iron (density about 8), rock (density about 3), and ice (density about 1), etc. Source: Heibonsha World Encyclopedia, 2nd Edition Information |
太陽系内の多くの惑星,衛星の諸特徴を統一的に理解しようという学問分野。地上からの望遠鏡観測のデータに惑星探査機によるデータが加わり,急速に進歩しつつある。アプローチのしかたは,地球型惑星を観測して地球のよりよき理解を深める,あるいは太陽系の起源や生命の起源に結びつけていくなどさまざまの視点がある。いちばん古くからの議論は,観測から得られた(見かけの)質量と半径から平均密度を出し,金属鉄(密度約8),岩石(密度約3),氷(密度約1)などと比べて惑星本体のおおまかな構造をとらえようとするものであった。
出典 株式会社平凡社世界大百科事典 第2版について 情報 |
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