11.   Astronomers are the scientists who have detailed knowledge of comets and meteors.

12.   Astronomers are not sure, but they suspect they were seeing the aftereffects of a gamma-ray burst, the most powerful events in the universe today.

13.   Astronomers would be able to see Polaris more clearly than nearby Pasadena.

14.   At first, astronomers were wary, but the Swiss astronomers had checked their data with care.

15.   At first, the astronomers were not sure they could believe what they were seeing.

16.   Astronomers are the scientists who can lay claim to detailed knowledge of meteor showers.

17.   Astronomers are the scientists who lay claim to detailed knowledge of meteor showers.

18.   Astronomers are traditionally solitary, sometimes spending years following a single star.

19.   Astronomers had already been on the mountaintop for decades.

20.   Because professional astronomers are often too busy with their own research to help verify discoveries, the responsibility invariably falls on experienced amateurs.