On Sun, 26 Jun 2005 02:37:03 GMT, Stephen G. Giannoni
>Well that's comforting (really), but when do they stop referencing it
>as an "estimate" ....
Not for a long time. The window required for a strike is incredibly
small- smaller than the uncertainties introduced by gravitational
perturbations and various interplanetary drag sources. So an actual
collision needs to be fairly near term to know for sure. So these things
are treated probabilistically. In the case of MN4, the likelihood of a
strike in 2029 is extremely low- it can practically be treated as zero.
But the probability of a later collision is still impossible to
calculate with any accuracy. It is far easier to say that something
_isn't_ going to hit than that it _is_.
Chris L Peterson