We wouldn’t know if we had. Using most of our current techniques, you can’t actually determine the inclination of the orbits of the planets. The one exception is the occultation technique used by the Kepler satellite, in which case you know that the planet’s orbit is edge-on to the line of sight (that’s how it works), but if there were any other planets with orbits that weren’t edge-on, you wouldn’t know about them.
Thanks Chronos. I had thought that some of our exoplanet discoveries had been via observing them in transit across their sun? I seem to recall that we had arrived at an estimate of the composition of an exoplanets atmosphere that way? So presumably if we see an exoplanets transit, we could tell what is orbital path is?
Excavating - I have always thought ‘solar system’ was pretty generic shorthand for any system with a sun and orbiting bodies?
Yeah, those are the ones discovered by the Kepler satellite, and we can tell something about its orbital path, in that we know that we’re on its orbital plane. But we can’t tell which way it crossed in front of the star: We just see the star dim and then brighten again with time. Our resolution isn’t nearly good enough to see a little black dot moving across a bright circle, or anything like that.
The Terrestrial Planet Finder mission, which could image planets directly, would be able to tell us all the details of a planet’s orbit. But given the current funding situation, don’t hold your breath for anything like that to actually get launched.
EDIT: Oh, and the convention among astronomers is to use lowercase words for general sorts of objects, and the capitalized one for our own personal one. Thus, for instance, there are many suns, but only one Sun; many galaxies, but ours is the Galaxy; many moons, but only one Moon, and many solar systems, but only one Solar System.
Of course, the orbits of the planets in solar system is not defined by a flat plain - It’s just “pretty close”.
As the video demonstrates, the cross-plain motions tend to even out through gravitational interactions. Those interactions may not be much, but over billions of years, they do have an effect. Plus, of course collisions. All this conspires to bring bodies back to the average rather than away.