Polar Fireball Captured by Armagh Observatory Cameras

The fireball of 22nd November as imaged by the Polar Bear camera at the Armagh Observatory

At around 1 o'clock in the early hours of Sunday 22nd November a piece of space rock about the size of an apple moving at some 25 km per second entered the atmosphere somewhere over the north Atlantic ocean between Scotland and Northern Ireland. Friction with the upper atmosphere caused the small rock to glow with an intensity brighter than the planet Venus, thus creating a very bright shooting star or "fireball".

As it headed westwards, burning to nothing within a few seconds, it was picked up by the Armagh Observatory meteor patrol cameras set up by Apostolos Christou four years ago to investigate swarms of dust or "streams" that occasionally hit the Earth. At the same time, the trail of incandescent air and material that it left behind registered for a full minute on the apparatus of Bangor amateur radio astronomer Richard White as it reflected radio waves emitted from distant TV stations.

The fireball also crossed the field of the Observatory's Polar Bear cameras, a project conceived by astronomer Simon Jeffery to monitor the variability of stars in the area of sky around the Pole Star, Polaris. The extremely detailed views observed by the Polar Bear system, with a resolution of approximately 50 metres, show how material from the disintegrating object spread along and across its path.

Objects such as the one that created this fireball are fragments of comets and asteroids, remnants of the primordial building blocks of our solar system. These and their smaller siblings, meteoroidal dust, hit the Earth's atmosphere many times every day, only 100 km or so above our heads, yet the process of their destruction is so violent that it cannot be reproduced in a laboratory on the Earth. Monitoring the sky with different kinds of instruments helps scientists to understand this process and provides indirect information on both the object and the "parent" comet or asteroid as well. No-one can predict when the next fireball will be seen, and it is for this reason that the efforts of amateur astronomers world-wide, such as Richard White and others around Ireland, are vital to meteor science, more so than most other branches of astronomy.

In this case the relatively high speed of the meteoroid and its final fragmentation at high altitude is suggestive of a cometary source, though many fireballs would have orbits similar to those of the majority of near-Earth asteroids.

FOR FURTHER INFORMATION PLEASE CONTACT: John McFarland at the Armagh Observatory, College Hill, Armagh, BT61 9DG. Tel.: 028-3752-2928; FAX: 028-3752-7174; jmf at sign

arm.ac.uk.

Last Revised: 2009 November 26th