Authentic Science Fiction Monthly No. 52 — page 95: what you’re looking at

Machine-transcribed from the original scan — historical spelling and the odd misread are preserved.

AUTHENTIC SCIENCE FICTION in the air in the bottle there will be only darkness. When we see a beam of light passing through the air, we do so only because some of that light falls upon small specks of solid dust or motes, and is reflected by them in the direction of our eyes. We can only see, in fact, light which actually passes into our eyes and falls on the retina. Light which is going past us is invisible. DIFFUSED DAYLIGHT On Earth, during the hours of daylight, all the space around us seems filled with visible light as, indeed, it is, even more so than we think. The light filling our atmos- phere is the so-called “‘diffused daylight,’ light travelling in all directions so that from any given point some of the light will be travelling in the direc- tion of our eyes. Most of it, however, will be travelling in all the other possible direc- tions—as witness the fact that other obserevrs, standing in any position, will also see light at that point. The light that leaves the sun and reaches the surface of the Earth does most of its journey travelling in only one direction, i.e., the straight path from the 94 sun towards the Earth. Before it gets to the surface, however, it has to pass through several layers of various gaseous mixtures which surround the Earth. These layers vary con- siderably in density and are turbulent rather than static. The mirage phenomena show how such conditionson even a much smaller scale can alter the direction of light. So it comes about that by the time light from the sun reaches the Earth it is travelling every which-way. Light from the sun will not be diffused before it reaches the surface of a planet, and so, looking into space from that planet, light will only enter the eye if one is looking directly towards the sun or some other luminous body. In any other direction only blackness will appear, as in the picture in question. Moreover, on Earth, a hill will be brightly illuminated on the side facing the sun but by no means unlit on the opposite side, because some light will be travelling in such a direction as to illuminate that also. That, of course, we have all seen for ourselves. What we have not seen so surely is that on an airless planet the side of a hill away comicloooks.com