Viewing page 205 of 212

This transcription has been completed. Contact us with corrections.

80.

[[underlined]] Appendix G. [[/underlined]].

[[underlined]] Probability of Collision with Meteors [[/underlined]].

The probability of collision with meteors of "visible" size is negligible. This can be shown by deriving an expression for the probability of collision of a sphere with particles moving in directions at random; all having constant velocity; the expression being obtained on the assumption that the speed of the sphere is small compared with the speed of the particles.

If we accept Newton's estimate ^[[(7)]] of the average distance apart of meteors as being 250 miles, we have by considering collision between very small meteors of velocity 30 miles/sec, and a sphere one foot in diameter of velocity one mile/sec., moving over a distance of 220,000 miles, the probability as 1.23 x 10 -8; which is, of course, practically negligible. The value would be slightly greater if the meteors were considered as having a diameter of several centimeters, rather than being particles; but the probability would be less, however, if meteor swarms were avoided.

-------------

(7) Netwon ^[[editing mark to change order of "t" and "w" such that name reads "Newton"]], Encyc. Brit. 9ed. v. 16.