DinoD wrote:Curious: After the initial report of the Chelyabinsk Event it was quickly followed by curiously adamant (almost panicked) denunciations that the meteor over Russia had "any relationship" to 2012 DA14 that was passing through Earth's ring plane several hours later. I may be under a mistaken presupposition that astronomical bodies within a miniscule space of 3 days of each other are almost certainly "related" and definitely "associated" (i.e. concentrated meteor showers). These 2 by mere hours and late reports of another in the San Francisco Bay Area a few hours after the 2012 DA14 pass. Even a different trajectory hardly means they are not related given plenty of potential for an earlier breakup or collison in the DA14 orbit. I would expect anyevery NEO to have "relations" from either small breakups or "an in progress gathering". Big Media, of course, is a terrible source of credible news...as we even witnessed a few days before DA14 arrived that a CNN news anchor was wondering if the close passing of the asteroid was caused by 'Global Warming' (a particular marketing fever they seem to have). So my question for the gifted here is, "Why the instant denunciations by both the ESA & NASA before any observations, research and conclusions could even be gathered from the event itself?"
In fact, the bodies having radically different orbits demonstrates beyond reasonable doubt that they are unrelated. Certainly, bodies like DA14 can be tidally disrupted into two or more separate pieces. But those pieces will have virtually identical orbits. There is simply no plausible mechanism that could produce pieces with different heliocentric (or geocentric) velocities, inclinations, semimajor axes, etc. just before passing Earth. There are opportunities for three-body interactions over the period of many orbits to shift pieces into very different orbits, but there is no reason that the pieces would happen come together again at the Earth, just hours apart (that would be hugely more unlikely than the simple coincidence of a 10 meter body burning up in the atmosphere close to the passage of an unrelated asteroid, which isn't really all that unlikely at all).
I don't know what the ESA said. The very first comment by NASA, however, was made after the initial orbital parameters of the Siberian meteor had been determined, and therefore it could be stated with certainty that the two events were unrelated. By that point, scientists in the meteor research community had already determined that there was no association, either.
I would hardly characterize the comments by NASA or by various scientists as "panicked". As you note, science stories in the popular press are frequently very poor. I think there was simply an interest in heading off misreporting as much as possible.
It was previously recognized that DA14 has a small potential to produce a meteor shower, and the radiant for that shower has been calculated. (I didn't record any meteors from it, if there were any.) The problem is, there is very little to suggest that asteroids produce showers, for the simple reason that they don't typically have debris trails the way comets do. I'm sure that people in California are analyzing the recent fireball, and will quickly determine from its radiant alone if it could possibly be related to DA14. By far the most likely scenario is that it was simply a sporadic meteor. Fireballs of this sort happen every day, so there's nothing surprising about it occurring when a large asteroid happened to be passing.
