Night Astronomy Reflector or Newtonian Telescope

Reflecting telescopes use a mirror, not a lens to collect their light.  This mirror is highly polished and has a concave shape.  As starlight falls on this primary mirror it is reflected to a smaller diagonal mirror which sends light to the eyepiece.

The advantages of a reflector telescope is that a large mirror is relatively inexpensive to make compared to a lens.  Having a large mirror means you can collect light from very faint celestial objects such as distant galaxies and nebula and produce spectacular views of these faint objects.  The first time I looked at the whirlpool galaxy through a 20 inch reflector, I was amazed at all the detail I could see in the spiral arms of this distant galaxy!   There are a few disadvantages with using a reflector telescope.  Because the telescope tube is open to the air, the primary mirror and secondary diagonal mirror can get out of alignment.  This usually means making some adjustments the mirror alignment bolts each time you observe.  Another problem with large reflectors is that they can be very heavy.  Aside from these two things, reflector telescopes are wonderful instruments and a great way to view the heavens!

Check out this web page showing a wide range of Reflector Telescopes.

The path of Light through a reflector telescope.


              Reflector on an Equatorial Mount                                                                                  Large Dobsonian Reflector


Reflector on a Dobsonian mount

How increasing the diameter of your telescope mirror changes your view of a globular star cluster.

The primary mirror in a reflector telescope
























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