Steps and stars

The modern journey to the stars took its first steps, literally, in ancient Alexandria at the mouth of the Nile sometime in the third or fourth centuries BC.

Pharaoh's surveyor walked the length of the Nile, recording the distance in paces. These measured steps provided Eratosthenes, a librarian in ancient Alexandria in 245 BC, with a mathematical construct to determine, first, the size of the earth, and then the distance to the sun, writes Chet Raymo in his newest book, "An Intimate Look at the Night Sky" (Walker).

The ancient Greek used the distance derived from the surveyor's paces between Alexandria and Syene (now Aswan in Egypt) to compare the noon shadow in a well at midsummer. Employing geometry, he gave an incredibly accurate figure for the circumference of the earth and its distance from the sun. Raymo cites this accomplishment as "the beginning of science as we know it."

Astronomers have never looked back. They have honed their gaze, always building on previous discoveries, reaching farther and farther into the night sky to record objects at distances on an order of magnitude that the vast majority of humanity fails even to imagine.

But a sad irony for many in the industrialized world today is the fact that, because of light pollution, the night skies are almost as inaccessible to the naked eye as the collection of manuscripts in the library in ancient Alexandria was to the mass of impoverished humanity at that time.

A new generation of telescopes is being built (see story, right). Thanks to digitized images and online access, sightings of these great telescopes will be universal. Nevertheless I can't but envy the view possessed by any third-world farmer alone, at night in his field.

E-mail Ideas@csps.com

(c) Copyright 2001. The Christian Science Monitor