雅努斯和厄庇墨透斯是人们熟知的“暹罗双星”,它们在同一轨道上运行而且仅仅相隔50千米(31英里)——这距离比它们本身的半径还要短。
The moons Janus and Epimetheus are known as the " Siamese moons , " because they share the same orbit and are separated by only 50 kilometers ( 31 mi ) - that 's less than the radius of the moons themselves .