Part 6 — The Skimspeed and Weight of Earth

A cent of speed is one hundredth of a mile a minute and appropriate for describing the slow orbits around small bodies. If we shift our focus to larger bodies and faster speeds we may need to change units. The Taoist philosopher Laotzu once found himself in low orbit around the moon. According to one version of the story, upon being told that his speed was 56 miles a minute, the sage produced his calculator and by twice squaring the number of cents (5600), saw that its fourth power was 10¹⁵. From this, since each quartic unit is worth 10⁴ tons, Laotzu deduced that the Moon weighs 10¹⁹ tons.

Another version of the story has it that he did not calculate the weight of the Moon in tons at all, but did so in ocs. By twice squaring the miles per minute number (56), the sage saw that its fourth power was 10⁷ and remarking that each quartic mile-a-minute unit is worth 10¹⁵ oc, he drew the conclusion that the Moon weighs 10²² oc. In any case it amounts to the same weight.

Out in the garden at night, about an hour and a half past sunset, we sometimes see man-made satellites — starlike dots moving slowly on an approximately north-south line. We only see the low satellites and they all seem to move at about the same speed, quite close to the Earth's skimspeed. They would be moving exactly at skimspeed if they were in hypothetical circular orbit down here at the surface.

Skimspeed at Earth is 263 miles a minute. If I square that twice in succession I get approximately 4.8 ×10⁹ quartic units, each of which is worth 10¹⁵ oc in terms of weight. This tells me the earth's weight in gravity equal to that at its surface is 4.8 ×10²⁴ oc.

My weight at the earth's surface is 70 ocs. So in an order-of-magnitude sense, watching a satellite move gives me a way of comparing my weight, in surface gravity, with that of earth.