Determining the power of a telescope, or its ability to enlarge the apparent size of distant objects, is a fundamental calculation in astronomy. It is found by dividing the focal length of the telescope’s objective lens or mirror by the focal length of the eyepiece used. For example, a telescope with a focal length of 1000mm used with a 25mm eyepiece yields a power of 40x. This signifies that the observed object appears forty times larger than when viewed with the unaided eye.
The ability to magnify celestial objects unlocks details otherwise invisible to the observer. Higher power allows for closer examination of lunar craters, planetary features, and faint deep-sky objects. Understanding this calculation enables observers to select appropriate eyepieces for specific viewing goals. Historically, this ability allowed early astronomers to make groundbreaking discoveries about the cosmos, paving the way for modern astrophysics.
