When a knowledgeable amateur astronomer tells you that she has a 14-inch telescope, what does the number 14 refer to?
A) the number of times the image is magnified (how much bigger it looks)
B) the length of the main telescope tube
C) the focal length
D) the length of the eyepiece tube
E) the diameter of the primary lens or mirror

Question

Quizplus · Accepted Answer

The number 14 refers to the diameter of the primary lens or mirror. This is important because the larger the diameter, the more light the telescope can gather, which allows for clearer and more detailed observations.

When a Knowledgeable Amateur Astronomer Tells You That She Has