Wednesday, November 18, 2009

Fire Over the West

No, the season for forest fires is over... very much over.
GARIBALDI -- The first in a series of strong storms tore off rooftops, downed trees and sent several coastal rivers to or near flood stage late Monday and early Tuesday. Forecasters expect three more storms to arrive in rapid succession today, Thursday and Friday.

Monday's storm blasted the northern Oregon coast with 85- to 95-mph wind gusts. At the aptly named Cape Foulweather, a peak gust of 95 mph shrieked through the trees at 5:15 p.m. Waldport also clocked in with a 95 mph wind gust, and Clatsop Spit recorded a wind gust of 84 mph.
However, the cosmos has very different weather, which is, for the most part, indifferent to our seasons.
FIREBALLS AND METEORS: As forecasters predicted, the Leonid meteor shower peaked during the late hours of Nov. 17th, favoring sky watchers in Asia with an outburst of 100+ meteors per hour. Just as the outburst was dying down, an even bigger event took place over the western USA. Something hit Earth's atmosphere and exploded with an energy equivalent of 0.5 to 1 kiloton of TNT. Witnesses in Colorado, Utah, Idaho and elsewhere say the fireball "turned night into day" and "shook the ground" when it exploded just after midnight Mountain Standard Time. Researchers who are analyzing infrasound recordings of the blast say the fireball was not a Leonid. It was probably a small asteroid, now scattered in fragments across the countryside. Efforts are underway to measure the trajectory of the asteroid and guide meteorite recovery efforts.

Please visit for images and updates.
The link in the piece is to SpaceWeather's front page. The archival link to this piece is here, with further links to some cool pics of the electric blue morning clouds resulting from the vapor cloud caused by the detonation, and also some video clips.

Because of the proliferation of automatic and hand-held electronic cameras, there is now a better ability than ever to get accurate data on the trajectory of meteorites like this. The leads to a more refined search for fragments that might have reached the earth. Since some meteorites are very unusual looking, while others more closely resemble common rocks- at least to the untrained eye- there is a natural bias to oversample (find and collect) the unusual varieties, for example, nickle-iron and stony iron meteorites. Recovery of samples from documented falls, therefore, are of great interest to people who study these rocks from space: they give scientists a better statistical representation of what's out there. Which in turn gives us a better understanding of the composition of this big rock we live on.

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