If someone says they are using a 12-inch telescope,to what dimension of the telescope's size are they most likely referring?
A) Focal length
B) Diameter
C) Radius
D) Length of the tube

Question

Quizplus · Accepted Answer

When referring to the size of a telescope, most people are talking about the diameter of the main objective lens or mirror. The diameter affects the amount of light the telescope can collect and therefore the clarity and brightness of the image.

If Someone Says They Are Using a 12-Inch Telescope,to What