They turned their telescopes towards other nearby galaxies.他们把望远镜转向附近其他星系。Quasars are the highly energetic cores of distant galaxies.类星体是遥远星系的极为活跃的核心体.We still don't know how many galaxies there are in the universe....
By measuring the motion of the galaxies in a cluster, astronomers can infer the cluster's mass.通过测量星系在一个星系团内的运动,天文学家们可以推定这个星系团的质量。They turned their telescopes towards other nearby galaxies...他们把望远镜转向附近其他星系。Space fli...
spiky plants, such as cacti带刺的植物，如仙人掌All the cacti were in flower, so that the desert was a riot of colour.所有的仙人掌都开花了，整个沙漠里五彩缤纷。There we could see nothing but cacti.那里除了仙人掌我们什么也看不到....