astronomy to friends, colleagues or students, they always assume optical astronomy - looking through an eyepiece in the cold of a dark night in some open field or on the top of a hill. Indeed, the mention of the word observatory evokes images of a dome with an optical telescope inside. Of course, this is but one use of the word (an observatory can be meteorological or geological, as well as astronomical) and there are different kinds of telescopes.
An optical telescope is an instrument that is used to study the visible part of the electromagnetic spectrum, or ROY G. BIV. The visible spectrum is that part of the spectrum of wavelengths of energy between ~700 nm and ~400 nm (inclusive) that corresponds to what the human eye can detect. (One nm, or nanometer, is one billionth of a meter.) The longer wavelengths (~700 nm) correspond to the color red and the shorter wavelenths (~400 nm) correspond to the color violet. ROY G BIV is the grade-school acronym for each of the constituent colors of the rainbow - Red, Orange, Yellow, Green, Blue, Indigo, and Violet. Optical telescopes use optics, lenses and mirrors that manipulate light to focus it onto an eyepiece or photographic film or plate. More recently, film has given way to electronics, as in digital cameras, used to count the number of photons (light energy) hitting the dectector and producing an electronic image.
Radio telescopes, on the other hand, work with wavelengths of the electromagnetic spectrum too long to be seen by the human eye. Radio telescopes receieve the same sort of energy that radios do (hence the name). The wavelengths involved are much longer than those of the visible spectrum - from about 1 mm (0.03 inches) to hundreds of meters. Because radio telescopes are working with different wavelenths, the design of the "telescopes" are different and look like the familiar "TV dish" shape. In fact, radio telescopes are often called antennas.
This portion of our geoscience tour will introduce the use of both optical and radio astronomy. This tour includes related background science, as well as a virtual field trip, available via the links (located to the left) as follows:
Background
Optical and radio telescopes will be introduced and discussed, as well as the basics of the electromagnetic spectrum, and an introduction to the celestial coordinate system will be presented. The background information and references provided will not only better prepare you for the Field Trip itself, but will help you act as a guide to others as well (either in situ or elsewhere).
Field Trip
Massachusetts has many planetaria and optical astronomy facilities available to the public, as well as numerous clubs to help beginners view the night sky and even buld their own telescopes. Massachusetts is also fortunate to have radio telescopes that can be used by schools and amature astronomy clubs.
Building upon the provided background information, I have put together a virtual (or actual) field trip to several facilities highlighting key features demonstrative of both radio and optical astronomy. This field trip ends with a "star party" where a step-by-step guide for viewing the night sky will be followed. Specific locations and directions are also included for those who live in the general area and would like to explore the area first-hand.
FIGURE 1: Travel Map