A telescope is a device that allows us to bring distant objects
closer to us so that we can study them. A good example is the
many planets, galaxies, and stars in outer space. Some range
from $1 at the toy store to the $1.2 billion Hubble Telescope.
There are two types of telescopes. Refractors use a glass lens.
Reflectors use mirrors instead of a lens.
Let's take the different pieces of a microscope and see how
they work. The objective lens in a Refractor or primary mirror
in Reflectors gather incoming light and brings it to a focus.
The eyepiece takes that same light and magnifies it to take
up a large part of the retina of the eye. Thus, it takes a small
image and spreads it out to make it look bigger.
There are two general principles to any telescope. One is how
well it can collect light. The other is the magnification of
the image you are viewing. Collecting light is related directly
to the diameter of the lens. The more light collected, the brighter
the image.
Magnification is the ability to take an object as a far distance
and enlarge it so you can see it clearly. Any magnification
can be obtained by using different eyepieces depending on the
object you are trying to view.
Here is a simplified explanation. Obtain two magnifying glasses
and a piece of paper. Hold one of the glasses between you and
the paper. At this point, the image will be blurry and unreadable.
Take the second glass and place between your eyes and the first
glass. Moving the second glass up or down should bring the piece
of paper into view. It will be larger and upside down though.
Give it a try and see what happens.
