How do lenses in glasses and telescopes bend light to help us see?

Glasses and telescopes help by using curved transparent lenses to redirect light. A ray changes speed as it enters glass, so it turns a little; the lens shape steers many rays toward the right spot. In glasses, that spot is your retina; in telescopes, it is a tiny image your eye can examine.

The lovely trick is scale: a telescope’s front lens can be much wider than a child’s pupil, so it gathers more starlight before shaping it. Then a smaller eyepiece lets the picture spread across your view, making a far-off moon crater or planet edge easier to notice.