请按照如下条件描述一下太阳系行星的运动规律:
- 句话数: 2
- 每句话包含4个词语，以顿号分隔且每个词语内部用引号标出
- 所有词语需使用英语
user
"orbit", "revolve", "gravity", "planets"、"elliptical", "around", "sun", "due"

```
{
  "description": [
    ["orbit", "revolve", "gravity", "planets"],
    ["elliptical", "around", "sun", "due"]
  ]
}
```
assistant