The map shown below was furnished through the courtesy of the Ohio State Radio Observatory.

How are these different kinds of light generated? Radio waves, the longest waves, are generated by oscillating electric currents. The Short Wave or Microwave has a wavelength similar to that of sound through air. Infrared radiation (such as a hot stove) is produced by heated solids or the molecular vibrations and rotations in gases and liquids. Visible radiation is produced by rearrangements of the outer electrons in atoms. Ultra-violet light immediately joins the visible spectrum. X-rays have wavelengths of the approximate size of atoms and originate in the rearrangement of the innermost electrons in atoms. The gamma rays (?-rays) are the electromagnetic waves of highest frequency (and thus the shortest wavelength) and originate in the rearrangement of the particles within the atomic nucleus itself. Each of these different portions of the light spectrum presents a different view of our universe.

If we examine the heavens through the longer radio waves (several meters) the 'reading' we get is of a universe alive with radiant fog or haze in almost all directions. As we move to receivers of higher radio frequencies, certain shapes and forms begin to emerge or stand out from the general fog. The haze is thicker and more radiant in the direction of the galactic plane and is most bright at the galactic nucleus. The plane of our galaxy appears as a glowing archway across the sky. If we further increase the frequency, we can penetrate or see deeper through the fog and discover some discrete features. Now we find extended sources of radiation and at still higher frequencies point sources or 'radio stars' begin to show up that shine (at these frequencies) more bright than any other objects in the heavens, yet never seen by the human eye. At yet higher frequencies, we reach the Visual level of radiation, where bright point sources or stars are the main objects resolved. Beyond the visual window are the ultra-high frequencies of the x-ray and gamma ray wavelengths. These waves shine right through much of what we would call matter and indicate the sites of cataclysmic events and massive outpourings of energy beyond our comprehension.

Copyright (c) 1997-99 Michael Erlewine