Question: Would it be theoretically possible to deduce the
masses and distances of the other planets in our Solar System
solely by observing the movement of our Sun? (Looking at the
movement of the parent star is one way to detect exoplanets,
isn't it?) It is a bit harder because we are ‘in’ the Solar
System, but technically yes it is sort of easy to do. This is
how some of the moons of Jupiter were found before we sent
spacecraft there. We can look at the orbit of the parent star
and see if we can see wiggles in the periodicity of the orbit,
or see darkenings on the surface that would indicate an
eclipsing planet, for example. That would be a very interesting
project! It would be very complex to model with a 9-body system
to the first approximation, but I’m pretty sure we would be able
to see the effects on the sun from the larger planets. Maybe the
proximity would allow us to measure the smaller planets too. You
could probably even see things like orbital inclination of
planets by looking at the motion of t