1. Galaxies tend to clump together in clusters. 星系往往聚集形成星团。
2. They turned their telescopes toward other nearby galaxies. 他们把望远镜转向附近的其他星系。
3. This has led scientists to speculate on the existence of other galaxies. 这就使得科学家推测还有其他星系存在。
4. To explain this, they hypothesize that galaxies must contain a great deal of missing matter which cannot be detected. 为了解释这一点,他们假定银河系一定包含了大量无法探测到的不明物质。
5. Only galaxies with a spherical bulge—like component appear to accommodate supermassive black holes. 只有拥有球形膨胀物质的星系才可能容纳超大质量的黑洞。