planet: [12] A planet is etymologically a ‘wanderer’. The word comes via Old French planete and late Latin planēta from Greek planétos, a derivative of the verb planasthai ‘wander’. This was applied to any heavenly body that appeared to move or ‘wander’ across the skies among the fixed stars, which in ancient astronomy included the sun and moon as well as Mars, Venus, etc. The modern application to a ‘body that orbits the sun (or similar star)’ dates from the mid 17th century.
planet (n.)
late Old English planete, from Old French planete (Modern French planète), from Late Latin planeta, from Greek planetes, from (asteres) planetai "wandering (stars)," from planasthai "to wander," of unknown origin, possibly from PIE *pele- (2) "flat, to spread" on notion of "spread out." So called because they have apparent motion, unlike the "fixed" stars. Originally including also the moon and sun; modern scientific sense of "world that orbits a star" is from 1630s.
例文
1. The blue whale is the largest living thing on the planet .
シロナガスクジラは地球上で最も体の大きい生物である。
2.The chances of a planet surviving a supernova always looked terribly slim.
惑星が超新星爆発を避ける確率は常に非常に低い。
3.The planet is probably in orbit around a small star.
この惑星は小さな恒星を周回している可能性があります。
4.The new planet is about ten times the size of the earth.
新たに発見された惑星は地球の約10倍の大きさだ。
5.The planet Mars will be visible to the naked eye all week.