例句：

　　Space scientists and astronomers have taken another step forwards.

上海419论坛　　航天科学家和天文学家又取得了进展。

　　Early astronomers thought that our planet was the centre of the universe.

上海419论坛　　早期的天文学家认为我们的星球是宇宙的中心。

上海419论坛　　Astronomers know that Pluto and Triton have nearly the same size, mass, and density.

上海419论坛　　天文学家知道冥王星与海卫一拥有几乎相同的体积、质量与密度。

　　Astronomers will have to collect more spectra from these stars to confirm their suspicions.

　　天文学家们必须要从这些恒星上采集更多的光谱来证实他们的推想。