Southwest US Fireball – September 14

A brilliant fireball was observed over southern California, Nevada, Arizona and Sonora on Wednesday evening, September 14. Hundreds of reports have been submitted to the American Meteor Society, and even a few to this blog. The best site for learning more about this event and other fireball events is at the American Meteor Society. Their page dedicated to this fireball (including a map of all reported eyewitnesses) can be found here.

An eyewitness in southern California was able to get a video of the event.

Down in Hermosillo, Sonora, Mexico, Salvador Aguirre picked up the fireball on his all-sky camera. In the image below, the fireball is seen low on the horizon to the NNW of Hermosillo.

September 14 fireball seen from Hermosillo, Mexico. Image taken by Salvador Aguirre with his all-sky meteor camera. Credit: Salvador Aguirre.

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So what caused the fireball? Most likely it was a small asteroid, no bigger than a basketball, hitting the upper atmosphere at 20-40 km per second. Based on the behavior of similar objects, it first became visible at an altitude of ~90 km and ceased to be visible at an altitude of ~20-30 km. Though some material may have survived to impact the ground as small meteorites, at least 90% or more of the asteroid burned up in flight.

About Carl Hergenrother
I am a professional astronomer specializing in the study of comets, asteroids and meteors. This blog will focus on my professional and amateur work in this field

3 Responses to Southwest US Fireball – September 14

  1. JFF says:

    Hi,

    >hitting the upper atmosphere at 20-40 km per hour

    This speed seems a bit low or am I missing something?
    Cheers.

    • Carl Hergenrother says:

      Ha! Nope, you’re not missing anything. The post should read 20-40 km per second. Thanks for catching the error.

  2. dane says:

    cool ! neat ! interesting , I like it ! just this moment I found out about it (2-26-12) , to me it is a late candle for my b-day ( 9-14 ) . thanks !!

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