Many new stargazers believe the most important specification of a telescope is magnification. Not so. The main purpose of an astronomy telescope is to collect light… to make faint images brighter and sharper. A telescope uses a lens or mirror to collect light, and the bigger the lens or mirror (called the objective) the better the image will be. Larger-aperture objectives are critical if you want to see faint galaxies and nebulae in the deep sky. And they also allow higher magnification and resolution of fine detail on planets and the moon. But there’s a trade-off in cost and size. This video takes you through the basics, and shows you a refractor, a reflector, and a compound telescope.