When you enter a new scientific field, you almost always find yourself with a new language and new technical terms to learn before you can understand what the specialists are saying. This is absolutely true in astronomy, both in terms of reference to the cosmos and in terms of describing the tools of the trade, the telescope being the most common. Let’s define some of the key terms that relate to telescopes to help you understand the most common terms more easily.
The first area of telescope specialization concerns the types of telescopes people use. The three models of telescopes that most people use are the refractor, the reflector, and the Schmidt Cassegrain telescope.
Refractor Telescope: Uses a convex lens to focus light onto the eyepiece.
Reflector Telescope: Has a concave lens, which means it bends inward. It uses mirrors to focus the image you ultimately see.
Schmidt-Cassegrain Telescope: Uses a system of mirrors to capture the image you want to see. It is a mixture of technology between the refractor and the reflector. There is a concave primary mirror and a convex secondary mirror. This telescope is an evolution of the reflector telescope.
Binocular Telescope: Uses a set of telescopes mounted and synchronized so that your view of the sky is in 3D.
Collimation: A term that indicates how well the telescope is tuned to give a good, clear image of what you are looking at. A telescope with good collimation so as not to have a false image of the celestial body.
Aperture: Describes the size of your telescope’s lens. This is an important term because the objective aperture is the key to how powerful your telescope is. Enlargement has nothing to do with it, it’s all in the opening.
Mount and Wedge: These two terms refer to the tripod that your telescope sits on. The mount is the actual tripod and the wedge is the device that allows you to attach the telescope to the mount. The stand and wedge are here to help you enjoy premium viewing and to protect your valuable telescope from a fall.
Altazimuth Mount: Refers to the tripod of the telescope that holds the device in place and makes it useful during a stargazing session. The altazimuth mouth allows the telescope to move both horizontally (which is the azimuth) and vertically. This way you have full range to look at things near the horizon or directly overhead.
Planisphere: A detailed star map of where everything is in the cosmos.
These are just a few of the basic concepts of telescope operation and astronomy. We have deliberately chosen those you need to know in order to discuss telescopes intelligently, but this glossary will be added to as time goes on. Your learning in the more complex aspects of astronomy and the design and operation of telescopes will continue for as long as you practice astronomy.