The primary mirrors in the 10-m Keck telescopes consist of
A) a large hollow honeycomb of glass-lightweight but relatively thick to prevent sagging.
B) a large, thin slab of glass whose surface is continuously adjusted by computer-controlled motors.
C) six individual mirrors, mounted so that they all bring the light to the same focus.
D) 36 individual mirrors, mounted so that they all bring the light to the same focus.

Question

Quizplus · Accepted Answer

The primary mirrors of the 10-m Keck telescopes are made up of 36 individual hexagonal segments. These segments are mounted together to act as a single, large mirror, with each segment being adjusted in real time by computer-controlled systems to maintain the correct shape and focus. This design allows for a large collecting area without the weight and structural issues of a single, massive mirror.

The Primary Mirrors in the 10-M Keck Telescopes Consist of