Monday, October 12, 2009
Universe in Stereoscope
If we direct our tele-stereoscope at the moon or any other celestial object, we shall fail to obtain any illusion of relief at all. This is only natural, as celestial distances are too big even for such instruments. After all, the 30- 50 cm distance between the two lenses nothing compared with the distance from the earth to the planets. Even if the two telescopes were mounted tens and hundreds of kilometers apart, we would get no results, as the planets are tens of millions of kilometers away. This is where stereoscopic photography steps in. suppose we photograph a planet today and take another photograph of it tomorrow. Both photographs taken from the same point on the globe, but from different points in the solar system, as in the space of 24 hours the earth will have traveled million of kilometers in orbit. Hence, the two photographs will not be identical. In the stereoscope, the pair will produce the illusion of relief. As you see, it is the earth’s orbital motion that enables us to obtain stereoscopic photographs of celestial objects. Imagine a giant with a head so huge that its intraocular distance ranges into millions of kilometers; this will give you a notion of the unusual effect astronomers achieve by such stereoscopic photography.