In article orfairbairn-D1D523.23453718112012@70-3-168-
216.pools.spcsdns.net, says...

In article
,
bob haller wrote:

if one of those loose planets ever visited our solar system it could
cause a disaster, such a large body could alter the earths orbit

Not too likely, unless it came into close proximity of the Earth. Such a
planet would enter at superorbital speed, pass perihelion, and then fly
off into space, never to return.

Theres a asteroid following earth, a visiting large planet could and
probably will change the planetary alinement

Insufficient gravitational attraction. Do the orbital mechanics!

Good luck trying to get Bob do do the math. He does all of his analyses
by "gut feel". If the data we present here doesn't fit his world view,
he ignores it.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer