The picture shows six of the nine planets in the solar system.

这张图片展示太阳系9个行星中的6个行星。

《柯林斯英汉双解大词典》

Scientists have launched many spaceships to explore other planets in the solar system.

科学家们已经发射了很多宇宙飞船去探索太阳系的其他行星。

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Mars is one of the four planets in the solar system that is a rocky planet.

火星是太阳系中四颗岩态行星之一。

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So there are eight planets in the solar system, not nine and not 10.

NPR: Pluto, the Un-Planet?

That's when there was the news about 12 planets in the solar system and possibly more, you know, coming.

NPR: Astronomers Prepare to Fight Pluto Demotion

Without a new nomenclature, these discoveries raised the prospect that textbooks could soon be talking about 50 or more planets in the Solar System.

BBC: NEWS | Science/Nature | Astronomers name 'world of chaos'