
The question asks to identify the term for a person who studies stars and planets. Let's examine the options:
Based on this analysis, the correct answer is: Astronomer.
Fill in the blank with the correct option. 
The teacher believed that the student’s sudden lack of interest in class was an ..........., as he had always been enthusiastic and attentive.
What comes next in the series? 
\(2, 6, 12, 20, 30, \ ?\)