Alberta Grade 9 Science PAT Practice Test

Reflecting telescopes use mirrors to collect and focus light, and mirrors can be built very large while staying relatively lightweight. This means you can create a telescope with a large aperture, which gathers more light and tightens the diffraction limit, giving brighter and sharper (clearer) images. Because mirrors reflect all colors the same way, there’s no chromatic aberration to blur colored edges around objects, which helps maintain image clarity as you build bigger instruments. That combination—large aperture possible with mirrors, plus minimal color distortion—is why an advantage of reflecting telescopes is that they can be made big and yield clearer images. Light loss and maintenance considerations exist (mirror coatings wear, alignment can be needed, and not every design is cheaper in every case), so those factors don’t trump the main benefit of scalable, high-quality image performance.