Giant Impact Crater Found In Australia

An anonymous reader writes "One of the largest meteorite impacts in the world has been discovered in the South Australian outback by geothermal researchers. It may explain one of the many extinction events in the past 600 million years, and may contain rare and exotic minerals. The crater is said to have been 'produced by an asteroid six to 12 km across' — which is really big!"

But how much energy is that?

[Zaphodox]

Okay so they give widely varying estimates of the crater's size - assuming the centre value of 120 Km a +/- 60 Km ia one hell of a margin of error. I imagine that the energy released from such an impact is orders of magnitude greater than any nuke we could ever throw at each other. The article metions the release of CO2, but i thought that by definition asteroids were just lumps of rock. So where does the CO2 come from after the impact?

Re:But how much energy is that?

[Trogre]

I would guess the ground. When a meteor hits land, a lot of the ejected material is from the ground, not the meteor itself. Rocks apparently have a lot of oxygen and carbon locked up in them.

Re:Meh, I've seen bigger...

[Anonymous Coward]

I've always wondered what damage we'd see if an asteroid that size is dropped from a height of 1km. Would there be devastation (apart from those directly in the firing line)?

Re:discovered?

[flyingfsck]

That impact crater is dwarfed by some other structures on earth: The Bushveld complex in South Africa is several hundred kilometers across, but it is so old (> 2 billion years = half the age of the earth) that it is not clear how it formed. Either a gigantic volcano, or a gigantic metor impact could have caused it.

Re:What would an impact look like?

[careysub]

On TV you see lots of computer sims but none look realistic to me. Would there be a light covering the sky so bright you couldn't see it or would it traverse the atmosphere so quick it wouldn't have time to heat up and you really would see this huge space rock impact. And what would the explosion look like? WOuld it be a fireball initially or would you simply see billions of tons or rock being launched into orbit?

A very useful source of information is the Asteroid Impact Effects on-line program: http://impact.ese.ic.ac.uk/ImpactEffects/ [ic.ac.uk]

Taking their upper size estimate (12 km) and average impact parameters (17 km/sec, 45 degree angle of entry) this would light up brilliantly at around 120 km altitude and get brighter all the way down its 10 second transit to the Earth. However you would probably not want to be anywhere you could actually see its entry. At a distance of 1250 km you would just see it light up on entry on the horizon, and thereafter the glow would be indirect until impact. THEN - part of the fireball which appear ~5 times larger and brighter than the Sun would rise above the horizon and irradiate you for about half an hour. This would be quite uncomfortable - a first degree thermal burn would develop after several seconds, but you get roasted for a hundred times longer than that, or until the fine ejecta thrown into space comes down and starts blocking your light after 10 minutes of so. And an hour after the impact a 12 psi blast wave with tornado-speed 335 mph winds would hit. This would likely be fatal.

Not uncommon

[confused one]

For what it's worth, these craters are probably not as uncommon as people think. I'm sitting inside one [wikipedia.org] right now.

Re:Not uncommon

[Push Latency]

I've always wondered if the odd, round-shaped area in the "Northeast Kingdom" of Vermont was one, though I've never mentioned it to anyone until now. I used to wallpaper my room with topographic and relief maps as a kid, and that has always rather stuck out whenever I look at a relief map of VT.

http://www.vermont-map.org/vermont.jpg [vermont-map.org]

Re:Meh, I've seen bigger...

[dachshund]

You wouldn't have ash encircling the planet and blocking out the sun as with a Chicxulub-type impact (which is by far the most devastating effect of a large asteroid impact to life on a planet), although you may still get some smaller Eyjafjallajokull-size ash clouds. Now if it landed in the ocean you'd have serious mega-tsunamis that would wipe out of a lot of coastal areas all around the world, but again not devastating on a planetary scale.

Well, don't take it as fact, but the geologist who discovered this said (from the TFA):

"Nothing within a few hundred kilometres of the blast would have survived, but more importantly the climate of the entire Earth would have been changed. It would have filled the atmosphere with so much dust that sunlight would be obscured, possibly for several years, killing a large amount of plant life on which animals obviously rely, thereby causing a global kill event - although perhaps not on the scale of the impact that wiped out the dinosaurs."

Also, there was a recent study [indiatimes.com] that suggested an asteroid impact in the ocean could cause massive devastation of the ozone layer, with all sorts of nasty effects for plant life. That was for a 1km asteroid. Still theoretical, but interesting to note.