宇宙苍穹

　　In trying to comprehend our universe, just how big is big? How far is far? This users guide to the cosmos will bring the incomprehensible down to a human scale such as Venus melting a tank, the density of a black hole compared to 1000 cars in a Coke can, and the comets in the Solar System equated to grains of sugar weighing half a ton或人在牛奶场找到一份事情，第一天放工，老板给他一只桶和一条凳让他去牛奶棚挤奶，他快乐地领命而去。放工的时刻，老板见他被溅了浑身的牛奶，并且那条凳子腿也断了，就问他：“怎样，这活挺难吗？”