The Fireball of 21 September 2012

Something dramatic happened in our skies on Friday evening.I missed seeing it myself  so I’m quite green with envy of the reports from eye witnesses of  spectacular fireballs racing through the night.

Image of meteor

A bright Aurigid meteor photographed in 2007 (Image credit:NASA/SETI Institute)

 

So what were these bright balls of light?From collated reports this sight is thought to have been a meteor (or even a bit of man-made space junk) breaking up.A meteor, sometimes more commonly known as a shooting star or more rarely as a fireball or bolide, is a small particle of metallic or stony matter, usually about the size of a grain of rice or smaller, burning up in the Earth’s atmosphere.When these particles are travelling through space they are known as meteoroids.When larger pieces of space debris land on Earth these fallen fragments are known as meteorites.

Million of meteors occur in the Earth’s atmosphere everyday.If you watch the sky on a dark, clear night, sooner or later you will see a shooting star whizz across the darkness, in fact if you keep watching the sky you’ll probably see several in an hour.They are visible when they are between 65 and 120 km (30-60 miles) above the Earth’s surface.As these bits of space debris reach the Earth they are travelling at high speeds, usually between 12-70 km/s (7-43 miles per second).As meteoroids travel through the atmosphere, air resistance creates friction causing the material to become heated until it is white hot and therefore giving out light.Most often the meteor is vaporised in the process.

Shooting stars are rare and wonderful sights and now you know just how spectacular an event you have just witnessed (or missed)!Please share your experience of this spectacle in the comments section, we’d love to hear what you saw, if you have any pictures of the fireball to share please let us know.

We receive so many enquiries about meteorites that we have a special webpage of common questions. You may also find this video of the last meteorite found locally of interest.

Fireballs can be reported to Armagh  Observatory.

UPDATE:Colin Campbell’s spectacular photo of this event is our Image of the Month.

UPDATE (26 September 2012):Based on analysis of the fireball’s speed it seems to have not been man-made spacejunk (satellites are slower than meteors, see our show Beyond the Blue for more on this). The fireball amost certainly was a meteor, possibly even a very small member of the Aten asteroid family. Atens are Near Earth Objects which have orbits mostly or entirely inside that of Earth.