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.更多《欧美AV毛片》完整版无删减、欧美AV毛片中文完整版、欧美AV毛片在线观看完整版免费相关欧美综艺资源，请持续关注CPP阳光影视!