What characterizes a refracting telescope?

A refracting telescope is characterized by its use of lenses to gather and focus light. This optical design includes an objective lens at the front of the telescope that bends, or refracts, incoming light to a focal point. The eyepiece lens is then used to magnify the image formed at this focal point for the viewer.

This design leads to the characteristic clear and sharp images that refractors are capable of producing, particularly for viewing celestial objects. The use of lenses allows for effective light gathering and focusing, making refracting telescopes suitable for various astronomical observations, whether they are earth-based or not.

The other options describe features that do not apply to refracting telescopes. Some telescopes use reflective surfaces, like mirrors, to gather light, while others may utilize electronic sensors instead of optical systems. Furthermore, while some telescopes are indeed primarily designed for observations on Earth, refracting telescopes can also be used in space-based applications, thus not being limited to earth-based observations.