plan‧et W3 / plænət, plænɪt / 名词 [可数名词]

1 a very large round object in space that moves around the Sun or another star :

Mercury is the smallest of all the planets.

Is there life on other planets?

the future of planet Earth ► Do not say ‘in a planet’. Say on a planet.

2 somebody is (living) on another planet/what planet is somebody on? spoken used humorously to say that someone’s ideas are not at all practical or sensible :

He thinks motherhood is glamorous – what planet is he on?

3 the planet the world – used especially when talking about the environment :

a safer future for the planet

— planetary 形容词 [仅用于名词前] :

the planetary system

THESAURUS

in the sky

star a large ball of burning gas in space, which can be seen at night as a point of light in the sky : The dark night sky was clear and full of stars.

planet one of the large objects that goes around the sun, for example the Earth, Saturn, Mercury, or Mars : The planet Uranus was discovered in 1781.

sun the star that gives us light and heat, around which the planets move. There are also many millions of other suns in the universe : The sun came out from behind a cloud. | a dying sun

moon the round object that moves around the Earth every 28 days, or a similar object that goes around another planet : The moon rose in the night sky. | Titan is one of the moons of Saturn.

asteroid a mass of rock that moves around the sun. Most asteroids are found between Jupiter and Mars : the asteroid belt

pulsar a type of star that is far away in space and produces radiation and radio waves

quasar an object like a star that is far away in space and shines extremely brightly

supernova a very large exploding star

constellation a group of stars that forms a particular pattern and has a name : The constellation of Orion is one of the most easily recognizable patterns of stars in the night sky.

galaxy one of the large groups of stars that make up the universe : Astronomers have detected a galaxy 11 billion light years away.

the universe all space, including all the stars and planets : How many planets in the universe have life?