What type of telescope uses a curved mirror as its primary light-gathering element?

Question

Accepted Answer

Reflecting telescope. A reflecting telescope uses a curved mirror (typically a concave parabolic mirror) as its primary light-gathering element. Light enters the telescope and is reflected off this primary mirror to a focal point, where it can be observed directly or directed to instruments by a secondary mirror. The Newtonian and Cassegrain designs are common reflecting telescope configurations.

A refracting telescope uses lenses, not mirrors, to bend and focus light. While radio telescopes also use dish-shaped reflectors, the question refers to optical telescopes using curved mirrors. A catadioptric telescope uses a combination of both mirrors and lenses (such as the Schmidt-Cassegrain design), making it a hybrid rather than a purely mirror-based system.

Telescope types and their optical principles are standard topics on the DSST Astronomy exam. Students should understand the advantages of reflecting telescopes over refractors (no chromatic aberration, easier to build large apertures, lighter construction) and why virtually all major research telescopes today use reflecting designs. Knowledge of specific telescope designs and their trade-offs helps students answer questions about observational astronomy.

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