"Jim Hawkins" wrote in message
m...
If there were another planet, same mass as Earth and in the same orbit but
at the precise opposite orbital position, we would presumably never see it
because it would always be eclipsed by the sun.
Is there any way we can be sure that there isn't such a planet?

Jim Hawkins


It would be detectable due to its perturbation of the orbits of other solar
system objects.