"How does a pansy, for example, select the ingredients from soil to get the right colors for the flower? Now there's a great miracle. I think there's a supreme power behind all of this. I see it in nature."
- ASLC Co-Founder, Clyde Tombaugh

Star Trails (Rich Richins) 

Telescope Basics

Observing Basics


  Quick Links

perture Fever

Astronomers love aperture (the diameter of a telescope). A larger aperture means a better view (and good views are what we stay out all night for). There are various mathematical models that describe how a telescope's aperture will affect the brightness and resolution of celestial objects. Rather than bore you with the theory, here is a simulated pictorial guide to what you can expect to see with telescopes of various apertures.

For this demonstration, we'll be viewing M101, a beautiful spiral galaxy in Ursa Major. All viewing will be done at 100 power.

Refractor Telescope

The image above is a CCD image of M101 taken through an 8" Schmidt Cassegrain Telescope

20 inch

A 20" Scope shows much detail (but no color)

10 Inch

A 12" will still reveal a fair amount of structure




8 inch

An 8" telescope still shows some of the spiral arms. Much of the detail is lost, but it still looks like a spiral galaxy.

4 inch

A 4" telescope shows only the central core and a hint of the brightest portions of the spiral arms