Jupiter, Saturn, Uranus, and Neptune. Those are the gas giants, the four heavyweights of the solar system. But was there once a fifth?

木星、土星、天王星和海王星。这些都是气体行星，是太阳系的四个重量级。但曾经存在第五个行星吗？

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Our planet Earth, together with other planets, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto revolve around our Sun in what is called our Solar system.

我们的地球和其他行星——水星、金星、火星、木星、土星、天王星、海王星、冥王星一起围绕着太阳旋转，构成所谓的太阳系。

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Jupiter, Saturn, Uranus and Neptune. Those are the gas giants, the four heavyweights of the solar system. But was there once a fifth?

木星，土星，天王星和海王星。这些都是气体行星，太阳系的四个重量级。但曾经存在第五个行星吗？

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Eventually, assuming the probes continued to function, they would pass and study Uranus and Neptune, and then depart the solar system.

FORBES: Magazine Article

To cap that, having looked at Jupiter and Saturn, Voyager 2's controllers decided to extend the mission by taking pictures of Uranus and Neptune as the craft continued on its journey out of the solar system.

ECONOMIST: The long arm of the celestial repairman