ことばのいずみ~Fountain of Language

(問) 文意が通るよう①から⑤を正しい順序に並べ替えよ。

①Thus, planets vary widely in size, composition, atmospheric conditions, and number of satellites. Unlike stars, which generate their own light, planets are visible because they reflect starlight. Understanding these distinctions is essential for grasping the diversity of celestial bodies in the universe.

②A planet is defined as a celestial body that orbits a star and meets specific criteria. In modern astronomy, these criteria are threefold: it must orbit a star, possess sufficient mass for its gravity to shape it into a nearly spherical form, and have cleared its orbital region of other bodies. Objects that fail to satisfy these conditions are classified as dwarf planets, with Pluto serving as a well-known example.

③By contrast, the outer giant planets are much larger and consist mainly of gas and ice. Jupiter, the largest planet in the solar system, is notable for its massive storm known as the Great Red Spot. Saturn is distinguished by its striking ring system, Uranus appears to rotate on its side due to its highly inclined rotational axis, and Neptune, the most distant planet, is known for its powerful winds.

④The solar system currently contains eight planets. In order of increasing distance from the Sun, they are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Based on their locations and physical characteristics, these planets can be broadly divided into two categories. The inner four are terrestrial planets composed primarily of rock, whereas the outer four are giant planets made up largely of gas and ice.

⑤The inner terrestrial planets are relatively small and share the common feature of having solid surfaces. Mercury, the closest planet to the Sun, exhibits extreme temperature variations between day and night. Venus is enveloped in a dense atmosphere, leading to exceptionally high surface temperatures. Earth is unique in that it harbors liquid water and supports life, while Mars, known for its reddish appearance, has been extensively studied for evidence of past or present water and life.





【正解】

②A planet is defined as a celestial body that orbits a star and meets specific criteria. In modern astronomy, these criteria are threefold: it must orbit a star, possess sufficient mass for its gravity to shape it into a nearly spherical form, and have cleared its orbital region of other bodies. Objects that fail to satisfy these conditions are classified as dwarf planets, with Pluto serving as a well-known example.

④The solar system currently contains eight planets. In order of increasing distance from the Sun, they are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Based on their locations and physical characteristics, these planets can be broadly divided into two categories. The inner four are terrestrial planets composed primarily of rock, whereas the outer four are giant planets made up largely of gas and ice.

⑤The inner terrestrial planets are relatively small and share the common feature of having solid surfaces. Mercury, the closest planet to the Sun, exhibits extreme temperature variations between day and night. Venus is enveloped in a dense atmosphere, leading to exceptionally high surface temperatures. Earth is unique in that it harbors liquid water and supports life, while Mars, known for its reddish appearance, has been extensively studied for evidence of past or present water and life.

③By contrast, the outer giant planets are much larger and consist mainly of gas and ice. Jupiter, the largest planet in the solar system, is notable for its massive storm known as the Great Red Spot. Saturn is distinguished by its striking ring system, Uranus appears to rotate on its side due to its highly inclined rotational axis, and Neptune, the most distant planet, is known for its powerful winds.

①Thus, planets vary widely in size, composition, atmospheric conditions, and number of satellites. Unlike stars, which generate their own light, planets are visible because they reflect starlight. Understanding these distinctions is essential for grasping the diversity of celestial bodies in the universe.

【和訳】

惑星とは、恒星の周りを公転する天体のうち、いくつかの条件を満たしたものを指す。現代の天文学では、第一に恒星の周りを回っていること、第二に自らの重力によってほぼ球形になっていること、第三にその軌道周辺から他の天体を排除していることが求められる。これらの条件を満たさない天体は準惑星と呼ばれ、代表例として冥王星が挙げられる。

太陽系には現在、八つの惑星が存在する。太陽に近い順に、水星、金星、地球、火星、木星、土星、天王星、海王星である。これらは位置と性質によって大きく二つに分けられる。内側の四つは岩石を主成分とする地球型惑星であり、外側の四つはガスや氷を主成分とする巨大惑星である。

まず、内側の地球型惑星は、比較的小さく、固体の表面を持つ点に特徴がある。水星は最も太陽に近く、昼夜の温度差が非常に大きい。金星は厚い大気に覆われ、表面温度が極めて高い。地球は液体の水と生命を有する特異な存在であり、火星は赤い外見で知られ、水や生命の痕跡を探る研究が進められている。

これに対して、外側の巨大惑星は非常に大きく、主にガスや氷で構成されている。木星は太陽系最大の惑星であり、巨大な嵐である大赤斑を持つ。土星は美しい環で広く知られ、天王星は自転軸が大きく傾いているため、横倒しに回転しているように見える。海王星は太陽系の最も外側に位置し、非常に強い風が吹くことで知られる。

このように、惑星は大きさや成分、大気、衛星の数などにおいて大きく異なる。また、惑星は自ら光を放つ恒星とは異なり、恒星の光を反射して見えている。こうした違いを理解することは、宇宙に存在する多様な天体の性質を知る上で重要である。