[X] My Assistant

[Guest_PhilCo126_*]

Astronomers declare to have detected the collision of two worlds:
"It's as if Earth and Venus collided with each other," said Benjamin Zuckerman, UCLA professor of physics and astronomy
http://www.physorg.com/news141401769.html

[nprev]

Hey, Gordan! Long time since we last batted an idea around, good to "see" you!

Yeah, I had considered light pressure and other effects, but I keep coming back to Saturn's rings and their apparent longevity, to say nothing of the other gas giant ring systems. There seems to be a large cardinal number of mechanisms to generate & maintain debris toroids in orbit around "parent" objects. For example, Jupiter's rings are maintained by collision with (and presumably reaccretion by) the inner small moons, and Saturn has just a whole bunch of things happening from Enceladus' eruptions to shepard/embedded moons depending on what part of the rings you're talking about. Then, of course, we have the Asteroid Belt; in fact, we also have the Zodiacal Light, so there is a reasonably large amount of dust still in our own Solar System that has not yet been eroded. Not convinced that we understand all the possible mechanisms yet is all.

I would actually be delighted (if that's appropriate!) if this system did in fact experience a collision between two worlds of terrestrial mass. What bugs me, though, is that such events would seem to be relatively common during the early stages of planetary system formation (as Doug pointed out with the Moon reference), but not so much later on. If this is an evolved system comparable in age to our own, I have a hard time understanding why this happened so late in the system's history; statistics say that it should have happened much earlier if it was going to happen at all, absent of external influences such as passage of a nearby star.