Earth Science: Geology, the Environment, and the Universe

Chapter 28: The Sun-Earth-Moon System

Problem of the Week

The Eyes Have It

For centuries, humans studied the heavens with only their eyes. The eye is a complex and intricate organ, but it is limited in many ways and lacking in its ability to see into the far reaches of space. As you know, the human eye can detect electromagnetic radiation in a very narrow range of wavelengths called visible light, as shown on page 749 in your text.

Astronomers have been challenged to study a vast universe from the confines of our planet using just the human eye. Much of our knowledge of space has been gained through the use of the human eye. However, the invention of the telescope, and the ability to use telescopes to collect various wavelengths of electromagnetic radiation has enabled us to see far into space. Technology has given us the ability to collect more information than we could have with our eyes alone.

Problem:

Telescopes have been adapted to collect various wavelengths of electromagnetic radiation. The two types used to collect visible light are reflecting and refracting telescopes. Diagrams and descriptions of these two types of telescopes are found on page 749 of your text. Astronomers primarily use reflecting telescopes because they do not have the size limitations that refracting telescopes do. Refracting telescopes are limited in size because of the difficulties in manufacturing a large, flawless glass lens and the problem of supporting a large lens along the edges. The mirrors for reflecting telescopes are easier to manufacture and can be supported from underneath.

1. Take a look at the two diagrams of the refracting and reflecting telescopes on page 749.


2. Do some research. Identify the parts of the human eye, and investigate how it functions. For this information, use the Web sites below.


3. Determine which telescope, refractor or reflector, is more similar to the human eye.


4. Write analogies for each part of the telescope you choose and the parts of the eye.
   • Just for Kids: How the eye works
   
   
   • How the Body Works (the Eye)