Mars's orbit around the Sun is the fourth fastest orbit of all the solar system planets.

在太阳系所有行星中，火星绕太阳的轨道速度第四快。

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The red planet is the most Earth-like of solar system planets, with a comparatively similar size and temperature range as our own planet.

这个红色的星球是太阳系中和地球最类似的行星，它和我们居住的星球有着相似的大小和温度环境。

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Some scientists have called Jupiter the protector of the inner planets and our own Earth -- from objects from the outer solar system.

VOA: special.2009.08.25

Mr.Lissauer says the five inner planets are among the smallest confirmed planets beyond our solar system.

VOA: special.2011.02.09

Or Venus? Or on any of the other planets either inside or outside our solar system?

VOA: special.2010.05.25

The test was designed to simulate the type of impact that would have been frequent during Earth's early history, some four billion years ago, when rocky, icy debris in our Solar System accumulated to form planets.

BBC: Comets could have seeded life on Earth

The Kepler mission has identified 132 planets beyond our solar system since its launch in 2009, leading scientists to believe that most stars in our galaxy have planets circling them.

CNN: Planet-hunting Kepler spacecraft in trouble

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

NPR: Pluto, the Un-Planet?