Limitations of the Human Eye

The human eye is a remarkable biological invention, a shining triumph of the process of evolution. Although the human eye was the detector that started us on mankind's exploration of the Cosmos, it has some shortcomings that ultimately limit that exploration:

1. The eye has limited size and therefore limited light-gathering power.
2. The eye has limited frequency response, since it can only see electromagnetic radiation in the visible wavelengths.
3. The eye distinguishes a new image multiple times a second, so it cannot be used to accumulate light over a long period in order to intensify a faint image.
4. The eye cannot store an image for future reference like a photographic plate can.

Astronomers have developed a variety of instruments and techniques to supplement the human eye and to alleviate these shortcomings. As a result, in modern research astronomy, very few observations are made any more by an astronomer looking directly through an optical telescope.