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》在线观看高清完整版视频、欧美AV毛片免费完整版在线观看高清、欧美AV毛片免费在线观看相关欧美综艺资源，请持续关注CPP阳光影视!