Mercury is surprisingly dense, apparently because it has an unusually large iron core. With only a transient atmosphere, Mercury has a surface that still bears the record of bombardment by asteroidal bodies early in its history. Venus has a carbon dioxide atmosphere 90 times thicker than that of Earth, causing an efficient greenhouse effect by which the Venusian atmosphere is heated.
- dense [dens] adj.密度大的
- iron core [ˈaiən - kɔ:] n. 由铁组成的核
- transient [ˈtrænziənt] adj. 瞬间变化的
- bombardment [bɔmˈbɑ:dmənt] n. 撞击
- asteroidal body [ˈæstərɔid - l - ˈbədi] n. 行星体
- carbon dioxide [ˈkɑ:bən - daɪˈɔksaɪd] n.二氧化碳
- greenhouse effect [ˈɡri:nhaus - iˈfekt] n.温室效应
- Venusian [vi:nˈju:siən] adj.金星的
