Tuesday, June 28, 2011

Peekskill Meteorite

You may not have known it, but yesterday (Monday, June 27, 17:00 UTC) a 10 meter diameter asteroid called 2011 MD passed within 12,400 km (7430 miles) of the Earth's surface.  For reference, that's about one Earth diameter away from us and about 31 times closer than the Moon.  There was no danger of it hitting but sometimes the Earth's gravitational field happens to catch one of these space rocks.  Here's the story of a much smaller meteorite which came crashing into the Hudson Valley 20 years ago.

On October 9, 1992, a meteorite entered Earth’s atmosphere somewhere over Kentucky, exploded into fragments, which continued over West Virginia, where it was first filmed at 11:48 pm.  The trajectory was toward the northeast, moving as a fireball through the skies over Maryland, eastern Pennsylvania, and finally crashing down to Earth striking a 1989 Chevy Malibu belonging to a Michelle Knapp at 207 Wells Street in Peekskill - a town in the in the lower Hudson Valley of New York (across the river from Bear Mountain).

At least 16 people in several states were able to film the meteorite fragments flying through the sky that evening.  The Peekskill fragment was the only one found, but there were others that didn't make such a conspicuous touchdown.

Check out this French website with all 16 known Peekskill meteorite videos.

Here's a picture of the 12.4 kg (27 lbs) meteorite after it struck the car (notice the red paint!).

From  R.A. Langheinrich Meteorites

The meteorite was sliced up for sale to collectors.  Here's one piece that was sold.

The meteorite was classified as an H6 chondrite - a rather ordinary meteorite that wouldn't have commanded such a high price without its amazing history.  Meteorites are traditionally classified as either iron, stony-iron, or stony.  Chondrites are a type of stony meteorite characterized by spherical chondrules which are believed to have originated as millimeter-scale molten droplets of silicate minerals (olivines and pyroxenes) freely floating in the early solar system.  The dust, small grains, and chondrules that make up the small asteroid parent body sources of these meteorites represent some of the earliest material from our forming solar system some 4.56 billion years ago.

Chondrites make up 86% of the witnessed meteorite falls, they're very common.  H-type chondrites are so-named because they have the highest total iron content (~30%) of the stony chondrites.  The 6 refers to the petrologic class of the meteorite - basically the amount of thermal metamorphism it experienced.  We may even know where all H-type chondrites come from, there's good evidence that collisions with an asteroid called 6-Hebe provided the raw material for these rocks.

The wealth of observational data allowed the velocity and orbital characteristics of this meteorite to be calculated.  It's pre-atmospheric velocity was estimated to be 14.72 km/s (almost 33,000 mi/hr!).  Prior to colliding with the Earth, its elliptical orbit around the Sun would have had a perihelion (closest approach to the Sun) of 0.886 AU and an aphelion (furthest distance from the Sun) of 2.1 AU (1.0 AU, or Astronomical Units, is the average distance of the Earth to the Sun - about 150 million kilometers or 93 million miles).

So, while having a meteorite strike your car may sound like a bad thing, it's actually like winning the lottery.  The car and meteorite were purchased at auction from Ms Knapp for about $100,000 (back in 1992) and have toured the world.  Here's a picture of the famous car and meteorite on display in a glass box (hence the reflections) in Paris.

A meteorite is welcome to strike the back of my car any time.

1 comment:

  1. Dear Madan sirs,
    Back in 1992 i tried contacting michele knaap but could not get thru via phone. The reason i wanted to contact her is due to the meteroite was estimated at 30 lbs and it happened several minutes before my 30 th bithday according to the usa today paper i was reading on oct 10th 1992 while working near ny city. My name is Tom McCreavy and i reside in north wales Pa. I kept the usa today article as i thought it was strange minutes before on my 30th birthday this took place. Born oct 10th 1962


    Tom Mc Creavy
    36 Belfast dr
    N.wales Pa 19454