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!