Fireball, but not XL5

Journal jd's Journal: Fireball, but not XL5 3

Journal by jd on Monday March 30, 2009 @02:43PM

Four fireballs, glowing blue and orange, were visible last night over the skies of the Carolinas on the southeast coast of the United States, followed by the sound of an explosion described as being like thunder. Reports of hearing the noise were coming in from as far afield as Connecticut. There is currently no word from NASA or the USAF as to what it could be, but it seems improbable that anything non-nuclear the military could put up could be heard over that kind of distance. It therefore seems likely to be a very big meteorite.

The next question would be what type of meteorite. This is not an idle question. The one slamming into the Sudan recently was (a) extremely big at an estimated 80 tonnes, and (b) from the extremely rare F-class of asteroid. If this new meteorite is also from an F-class asteroid, then it is likely associated with the one that hit Sudan. This is important as it means we might want to be looking very closely for other fragments yet to hit.

The colours are interesting and allow us to limit what the composition could have been and therefore where it came from. We can deduce this because anything slamming through the atmosphere is basically undergoing a giant version of your basic chemistry "flame test" for substance identification. We simply need to look up what metals produce blue, and in so doing we see that cadmium does produce a blue/violet colour, with copper producing more of a blue/green.

Other metals also produce a blue glow and tables of these colours abound, but some are more likely in meteoric material than others. Cadmium exists in meteorites. Well, all elements do, if you find enough meteorites. but it exists in sufficient quantity that it could produce this sort of effect. (As noted in the chemmaster link, low concentrations can't be detected by this method, however this is going to be vastly worsened by the fact that this isn't a bunsen burner being used and the distance over which you're observing is extreme.)

Ok, what else do we know? The fireballs were also orange. Urelites, such as the Sudan impact, contain a great deal of calcium, which burns brick-red, not orange. This suggests we can rule out the same source, which in turn means we probably don't have to worry about being strafed the way Jupiter was with the Shoemaker-Levy comet (21 impacts).

What can we say about it, though? Well, provided the surviving fragments didn't fall into the ocean, it means every meteorite hunter on the planet will be scouring newspaper stories that might indicate where impacts occurred. Meteoric material is valuable and anything on a scale big enough to be heard across the entire east coast of the US is going to be worth looking for. It had split into four in the upper atmosphere, so you're probably looking at a few thousand fragments reaching ground level that would exceed a year's average pay.

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