Disappointing news. The rock that Lisa Webber picked up after it bounced off her roof in the wake of the October 17 California fireball wasn’t a meteorite after all. NASA’s Peter Jenniskens, who helped in the identification writes this:
“We examined the rock with a petrographic microscope yesterday and quickly concluded it was not a meteorite. I sincerely thought it was, based on what appeared to me was remnant fusion crust. On closer inspection, that crust was a product of weathering of a natural rock, not from the heat of entry.”
Another specimen weighing 66 grams was found in the fall zone (Mill Valley area) by meteorite hunter Brien Cook on Monday, October 22.
Cook cut three slices from the rock earlier today, and there’s no doubt it’s the real item. The flecks of metal, the dark, shocked areas – if that’s not a meteorite I’ll eat a rock. To my eye it resembles the Park Forest (IL.) fall of March 26, 2003 which was classified as an L5 chondrite, a fairly common type of stony meteorite.
Meteorites are tricky. Like a Halloween costume, external appearances can mask a rock’s true identity. The Webber stone appears partially covered in a black fusion crust of melted rock typical of freshly-fallen meteorites. It even stuck to a magnet. Jenniskens peered under its disguise to reveal its real origin – Earth.
While the news is a bit of a let down, it does teach us how science works. Much as we’d like to believe our hunches about this or that aspect of nature, careful analysis may prove otherwise. Scientists and meteorite hunters alike know this is simply part of the process and move on. One question remains. What made the ding in Lisa Webber’s rooftop?
Speaking of roofs and shingles, ever heard of looking for tiny meteorites by sweeping a magnet through the grit that falls on your roof? Tomorrow we’ll explore the possibilities in Part II.
** UPDATE Oct. 25: In light of Brien’s find, Dr. Jenniskens has taken a second look at Lisa’s rock and is now convinced it’s the real thing after all. “An apology may have been too hasty,” said Jenniskens. “Lisa’s find is a genuine meteorite.” Ah, the tortuous path one must walk to find the truth!