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X and the City by John A. Adam

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Appendix 12

THE EARTH AS VACUUM CLEANER?

 

 

 

 

 

How effective is the Earth at clearing a path through “space matter” in its vicinity? This is of interest, of course, with regard to possible close encounters with asteroids, as discussed in Chapter 24. In order to get a handle on this problem, one major task is to determine how effective the Earth is at capturing “errant” asteroids. In order to do so, we will use some elementary physical principles and properties of conic sections.

Because of the gravitational attraction of the Earth (or any other sufficiently massive body), it can in principle “pull in” objects that are not traveling directly toward a head-on collision. This results in a capture cross section (CCS) that is at least as large ...

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