I agree it works, Sunken... just not in other galaxies. We are capable of seeing the induced wobble of large Jovian sized planets, and perhaps some smaller ones, in our Galaxy but the resolution to discern even huge stars in other galaxies is extremely limited.
Free-roaming planets have in fact been found.
Found? Or theorized to explain an unexplained observation? Can you provide evidence of these free-roaming planets. I have not seen any such evidence. I know about the micro-lensing phenomena that some have postulated to be "free-roaming planets" but we cannot even demonstrate enough lensing on solar planets to even be sure that we could tell its sign on an object thousands of lightyears away. Some astronomers have not even accepted gravitic lensing as proof of superdense dark stars.
Any free-roaming planets would tend to be moving with their surrounding objects... certainly not counter to the orbital velocity of the galaxy.
In addition, unless we postulate that our free-roaming planet comes only from the nearest stellar systems, we are talking about even further distances and longer times.
Rotation of our galaxy takes something like 25 million years. :')
You're off by an order of magnitude, Sunken... it takes 225-250 million years for one rotation of the Milky Way Galaxy (Galactic Year). That would be the time required for Sol to travel approximately 180 Light Years.
The average distance of any star to Sol is approximately 30,000 light years... at that rate, it would take a free-roaming planet from a star the average distance from us, moving at the orbital velocity of the galaxy (220 km/s at our distance from the center) relative to us toward us, approximately 38 BILLION years to arrive. The Universe is only 18 to 22 Billion years old... of course there are closer stars (a free-roaming planet from Alph-Centauri would take about 6,000 years at that rate... but what force would get it to move at that rate toward us? Gravity?) so it is possible, but the odds are extremely small.
Think about our solar system this way... imagine the sun is the size of a bowling ball... about 8"... in comparison, the earth is about 1/16th of an inch (half the size of a BB) and Jupiter is about 9/10"... Earth would be somewhere on an orbit about 78 feet away from the bowlingball and somewhere on a circle 245 feet around. Jupiter would be 405 feet away from the Bowlingball sun and poor demoted Pluto would be 3/5ths of a mile away. Now, throw several thousand of sand, one at a time, at this model solar system... what are the odds that you would hit the 1/16th inch sized Earth?
I would bet the odds of rolling snake-eyes 10,000 times in a row with honest dice are far larger than the odds of being hit by a extra-solar planet of sufficient mass to create the moon in the scenario given.
I think there is something else at work.
You're right, the galactic rotation does take that long, my apologies. My 25 million year figure refers to the Solar System's crossing the galactic plane, and is actually about 33 million years. Shoemaker suggested that the extinction-causing impacts on Earth came about as a direct or (more probably) indirect result of that oscillation.Rogue Planet Find Makes Astronomers Ponder TheoryEighteen rogue planets that seem to have broken all the rules about being born from a central, controlling sun may force a rethink about how planets form, astronomers said on Thursday... "The formation of young, free-floating, planetary-mass objects like these is difficult to explain by our current models of how planets form," Zapatero-Osorio said... They are not linked to one another in an orbit, but do move together as a cluster, she said... Many stars in our own galaxy, the Milky Way, may have formed in a similar manner to the Orion stars, she said. So there could be similar, hard-to-see planets floating around free near the Solar System.
by Maggie Fox
October 5, 2000
Think about our solar system this way... imagine the sun is the size of a bowling ball... about 8"... in comparison, the earth is about 1/16th of an inch (half the size of a BB) and Jupiter is about 9/10"... Earth would be somewhere on an orbit about 78 feet away from the bowlingball and somewhere on a circle 245 feet around. Jupiter would be 405 feet away from the Bowlingball sun and poor demoted Pluto would be 3/5ths of a mile away. Now, throw several thousand of sand, one at a time, at this model solar system... what are the odds that you would hit the 1/16th inch sized Earth?Over how much time / how many passes / how many other interactions (with Jupiter, for example)? Objects in orbit around the Sun can be in a variety of different planes; however, in the ecliptic, odds greatly improved. And I think we have some common ground as to using supposed odds of things happening as evidence of anything.