A telescope is a tool for observing objects in the distance, either in the sky or across land and sea. In this article, we will talk about telescopes for observing objects in the sky, to their natural beauty and to understand more about the nature of the universe in which we live.
It is useful to think of telescopes as "light buckets", whose main purpose is to gather as much light from a particular region of the sky as possible and to b.ing it into focus. For backyard astronomers, we are interested in observing sky objects in wavelengths visible to the human eye, that is, with an optical telescope (there are telescopes which observe other forms of light radio waves, microwaves, infrared, ultraviolet, x-rays and gamma rays, used by professional astronomers.).
There are two basic types of optical telescopes: reflectors and refractors, that are used by backyard astronomers. A third type, known as catadioptric combines the two.
To keep things simple, a reflector uses a curved mirror to collect the light and bring it to a focus at an eyepiece (see first figure at top of page). A refractor uses a lens, or a series of lenses, to focus the light at the eyepiece (see second figure at top of page). Combining the two types allows for a more compact telescope (shorter tube), but is a more expensive option (see figure at bottom of page).
There are many things to consider when contemplating the purchase of a backyard telescope, not the least of them, the cost (in dollars). For those interested in buying a telescope that is worth the expense, I refer you to the references at the end of this article.
A basic principle is to use your money on aperture (the size of the light-gathering mirror, or lens), rather than on magnification: seeing dim objects in the sky depends upon how much light is gathered. There are natural limits to magnification-at a certain point details, or resolution. exceeds the limits of the telescope equipment and our visual equipment (our eyes).
May you have clear skies!
[References: Night Watch: A Practical Guide to Viewing the Universe Revised 4*' Ed. Terence Dickinson Firefly Books 2013 (Basic)
The Backyard Astronomy's Guide 3'd Ed.
Terence Dickinson and Alan Dyer Firefly Books 2013 (More Advanced)
George Drake, M.D.
ETHOS Innovation Center Volunteer
Michiana Astronomical Society Member