天宫二号带着一款别致的“手表”——空间冷原子钟正在绕着地球翱翔。它仰望深空，俯视大地，探索浩淼宇宙遵循的黄金规则，细致描绘地球母亲的每一寸土地。这是人类史上首台在空间实验室开展科学研究的空间冷原子钟，它的精准度也是史无前例的，为3 000万年误差不超过1 s。这台原子钟是中国科学家们历经十数年孕育和抚养成才的，它承载着中国在空间定位、深空探测，以及广义相对论的验证等方面的研究使命。

The space atomic clock, a beautiful piece of “watch” in Tiangong two, looks up at the deep space, overlooks the earth, explores the vast universe following the golden rule, and gives a detailed description of every inch of the earth mother. It is the first space atomic clock to carry out scientific research of the space laboratory in the world, its precision is also unprecedented with error less than one second in thirty million years. This atomic clock is gestated and developed by Chinese scientists taking a dozen years, which carries our positioning, deep space exploration, verification of general relativity and other research assignments.