Second, Jupiter's enormous mass prevents most Sun-bound comets from penetrating the inner solar system.
其次，木星的巨大质量阻止了大多数与太阳结合的彗星穿透太阳系内部。
2
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。
3
The goal was to measure the AU; then, knowing the orbital speeds of all the other planets around the Sun, the scale of the Solar System would fall into place.