Planetary scientists have been racing to establish the origin of a bright fireball seen over parts of the UK on 14 September – the evidence now points to it being a meteor rather than re-entering space debris
Planetary scientists working to establish the origin of a bright fireball seen over Scotland, Northern Ireland and northern England on the evening of 14 September now believe the phenomenon was caused by a small piece of asteroid hitting the atmosphere. The idea that it was space junk re-entering the atmosphere is now looking less likely.
The spectacular event, spotted at about 10pm local time, was caught in numerous videos on social media, which showed a dazzling whitish-green light moving at speed across the sky, in some cases with a trail of glowing material behind it.
At the time of writing, around 900 eyewitness accounts had been submitted to an international catalogue of fireball events maintained by the American Meteor Society and the International Meteor Organization. Some observers even reported hearing a rumble following the event, which initial analysis suggests occurred over a region near the islands of Islay and Arran in Scotland.
Initially, it wasn’t clear if the fireball was the result of a meteoroid – a natural space rock – entering Earth’s atmosphere and becoming a meteor, or the re-entry of a piece of debris from human space activity, although some early evidence did point to the latter.
“[The fireball] had a very shallow entry angle, a substantial amount of fragmentation, which is typical of space junk, and it looks slowish. Space rocks tend to be a bit faster. However, we’re still crunching the numbers to get a good estimate on the velocity, which will tell us for sure whether this is space rock or space not,” said Luke Daly, a planetary scientist at the University of Glasgow, UK, and member of the UK Fireball Alliance, at the time.
However, a subsequent analysis of the fireball’s path by Denis Vida, a meteor expert at Western University in Canada, indicates that the fireball was the result of a space rock that dived through the atmosphere at a speed of nearly 32,000 miles per hour, or about 51,500 kilometres per hour.
“Meteors typically enter the atmosphere at very high speeds, 75 to 80 thousand miles per hour,” says John Maclean at the UK Meteor Network, whose cameras captured the phenomenon. This would equate to between about 121,000 and 129,000 kilometres per hour. “Space junk would be much slower, at maybe 25 to 30 thousand miles per hour depending on the original orbit velocity.”
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