domingo, 23 de setembro de 2012

Meteorites, space junk - or alien invasion?

The sight of unexplained fireballs in the night sky had some Scots wondering if this would become The Day The Earth Stood Still due to an alien encounter Photograph: Thomas Heaton/SWNS.com


SOME said it looked like a scene from the film Independence Day, others feared an aeroplane was crashing – but most simply stared at the sky in awed bewilderment at one of the most amazing astronomical displays ever seen over Scotland.


The emergency services were flooded by calls as a suspected meteorite shower lit up the skies. However, astronomers are still not sure exactly what happened late on Friday night, with some saying it might not have been meteorites but burning space junk – the disintegrating remains of satellites – falling to earth.

Concerned members of the public from Airdrie to Arbroath likened the bright lights they saw to flares, fireworks and the flaming debris from an exploded aircraft.

The lights were seen as far north as Caithness and by islanders on Skye, with sightings also reported in parts of central Scotland, including in Edinburgh and Glasgow. Other sightings were reported across parts of England and Northern Ireland, with one Twitter user describing seeing a "huge fireball" over Newquay in Cornwall.

Coastguards and police up and down the country were inundated with calls from around 11pm as people witnessed the slow-moving fireballs streak across the night sky, with some describing a loud "sonic boom" effect as they passed.

A spokesman for Forth Coastguard said: "From talking to other stations and to the RAF it's almost certainly meteorite activity. Calls came in from all over the place, thick and fast. We've had people report possible plane crashes, and others the weirdest fireworks they've ever seen. Folk just haven't known how to describe what they've seen. It's quite extraordinary."

People from Crail, Johnshaven and Arbroath had contacted them.

Clyde Coastguard said it had also received a "wee flurry" of calls reporting flares over Drummore, Airdrie and Brodick on Arran.

A spokeswoman said: "When we get it all over and at the same time then we attribute them to meteorites. There was meteorite activity forecast from September 15 to 21."

Jodrell Bank Observatory in Cheshire tweeted that there was "no real consensus on whether last night's spectacular fireball was a space rock burning up or space junk (bit of spacecraft)".

The Met Office tweeted that it believed it had been a meteorite.

Shetland Coastguard said a report of a flare at 11.10pm at Duncansby Head near John O'Groats was thought to be part of the meteor shower. Meteorites are also known as shooting stars because when they enter the Earth's atmosphere they heat up and emit light, giving the impression of a flare.

Explosions and rumblings are often heard during meteorite falls, which can be caused by sonic booms, as well as shock waves as the meteorite disintegrates. These sounds can be heard over areas of up to several thousand square miles.

Nicola Hopkin in Newton Mearns in Glasgow said she saw a long, slow-moving trail of yellow fire with a burning red circular tip passing through the sky accompanied by two sonic booms. "It looked like a plane had blown up in mid-air and was crashing. It was moving at an odd angle and seemed very low in the sky," she said. "It was incredible to see but a little frightening as I didn't really understand what I was looking at – I couldn't work out if it was a plane, a rocket, a meteor, a comet or what. When it was just out of my line of sight I heard what I thought were two gun shots or cars backfiring. They must have been sonic booms."

Brian Guthrie in Grangemouth said it had appeared to be something "pretty large breaking up in the atmosphere", and added: "I've seen shooting stars and meteor showers before, but this was much larger and much more colourful."

The lights were also clearly seen throughout the north of England, with people in Sheffield, Manchester, Leeds, and Blackpool taking to Twitter to record the event.

Harry Walker, 14, near Barnsley in South Yorkshire, said: "It appeared to be low in the sky and took quite a while to fly across the horizon. It was amazing. We didn't know what we had seen but then everyone on Twitter was calling it a meteor."

Tim O'Brien, associate director of the Jodrell Bank Observatory, said: "It was probably 80 miles up, burning as it entered the atmosphere. If anything did come down, it would have landed in the ocean."

Meteorite fragments have been found from Australia and Antarctica to the Sahara Desert and the Great Plains in the USA. Only a few hundred had been discovered by the beginning of the 20th century but there are now more than 30,000 in collections across the globe.

The effect of larger meteorite impacts – especially those made by iron meteorites – are responsible for a number of famous craters, including Barringer Meteorite Crater in Arizona, Odessa Meteor Crater in Texas, the Wabar Craters in Saudi Arabia, and Wolfe Creek Crater in Western Australia.


Fonte: heraldscotland.com

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