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Fear and wonder at Meteor Crater
By John Masters-Contributing writer
Flagstaff, Arizona-The chunk of space rock that created Meteor Crater wasn't anything like the one thought to have caused the extinction of the dinosaurs 65 million years ago. That meteor was massive: 10 kilometres wide. This one, which slammed into the earth about 55 kilometres east of Flagstaff, was just 45 metres across. But it was made of nickel-iron, so it weighed a hefty 300,000 tonnes, and it was travelling at 64,000 kilometres an hour. It hit with a force equal to setting off 20 million tonnes of dynamite. The circular gouge it carved into the flat landscape was nearly four kilometres in circumference and more than 200 metres deep. The strike produced winds in excess of 2,000 kilometres an hour and killed or flattened pretty much everything within about 20 kilometres.
That was 50,000 years ago. Today the hole it made is the world's most perfectly preserved meteor crater, thanks to its relative youth and the erosion-retarding conditions of arid Arizona.
It's also something of a rarity. The moon and Mars have meteor craters aplenty. We don't: our thick atmosphere burns up a lot of what comes our way from outer space and our weather systems erase the signs of what does make it through fairly quickly. Only about 150 meteor-impact sites are known on earth.
American astronauts have walked in Meteor Crater as training for the moon missions. We ordinary folk must content ourselves with the view from the rim, where a terrace and information centre have been built. Those eager to know more can listen to a talk given regularly on the terrace or browse the displays in the learning centre.
Meteor Crater is privately owned and operated, and not all such attractions are notable for the quality of information they impart, preferring instead to focus on the gift shop and food services. There is a large gift shop at Meteor Crater-and a fast-food chain restaurant-but its learning centre is remarkably good, comparing favourably with a similar institution overlooking another big crater, the state-run Jaggar Museum in Hawaii Volcanoes National Park.
The centre's exhibit looks at meteor craters on the moon and Mars, discusses the probable role a huge meteor had in making dinosaurs extinct and dramatically recreates the series of events that happened when the meteor landed just outside the window. There's also some unsettling information on the likelihood of another big object hitting us in the future. (Guaranteed, it's just a question of when. A meteor large enough to make a crater like this one may come along as often as every 1,000 years.)
One of the centre's most gripping demonstrations shows what effects space debris of various sizes, entering the earth's atmosphere at different angles, would have. You can program the visual display to depict everything from a pumpkin-size rock coming in obliquely to a 1,000-kilometre-wide mountain hurling straight down at us. The results? In the first case, the meteor skips harmlessly off the upper atmosphere, back into space. In the second, we blow up real good.
If you go
For more information on Meteor Crater visit its website at
www.meteorcrater.com.
For information on travel in Arizona visit the Arizona Office of Tourism website at
www.arizonaguide.com.
published on 03/24/2006
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