03 Music of the Celestial Spheres / The Moon and the Meteor Showers

4.5 billion years ago, a Mars-sized body (Theia) collided with the Earth, giving birth to the Moon. In their earliest days, both Earth and Moon were covered by vast magma oceans. Then came the Late Heavy Bombardment — a period when countless asteroids and icy bodies rained down upon the Earth. This violent era, when impacts within the solar system were especially active, ended about 4.1 billion years ago. With its close, the environment gradually became suitable for the establishment of life. Some of those meteorites may even have carried amino acids, forged beyond the Earth. It must have been a hellish spectacle — waves of molten magma crashing again and again — but there was no life yet to be harmed (or perhaps life arose and was extinguished many times over). 02 天体の音楽／月と流星群 45億年前に火星サイズの天体（テイア）が地球に衝突し、月が誕生。初期の地球と月はマグマ・オーシャンに覆われていた。そして、大量の隕石や氷が地球に降り注いだ後期重爆撃期（太陽系内の天体衝突が活発だった時期）が41億年前*に終り、生命の定着に適した環境が整い始めた。隕石には地球外で作られたアミノ酸も含まれていたかも知れない。灼熱のマグマ・オーシャンの津波が何度も襲うという地獄絵図が展開されたはずだが、生命はまだ生まれていなかったから心配はいらない（または何度も滅んだかも？）。