Question

Which are advantages of reflecting telescopes? Check all that apply.

There is no rainbow-like halo around the image.
Reflecting telescopes can be made very large.
Reflecting telescopes use only lenses, not mirrors.
Only the reflecting side of the primary mirror needs to be perfectly shaped and smooth.
The eyepiece creates an image for the observer.

Answer 1

Correct choices:
- There is no rainbow-like halo around the image. (True — mirrors do not produce chromatic aberration the way lenses do.)
- Reflecting telescopes can be made very large. (True — mirrors can be supported from behind, so much larger apertures are practical than with large lenses.)
- Only the reflecting side of the primary mirror needs to be perfectly shaped and smooth. (True — the optical surface is the reflective face; the back of the mirror does not need the same optical finish.)

Incorrect choices:
- Reflecting telescopes use only lenses, not mirrors. (False — they use mirrors, not lenses.)
- The eyepiece creates an image for the observer. (Misleading here — the eyepiece does form the final magnified image for the eye, but that is not an advantage specific to reflectors; refractors also use eyepieces.)