Asteroid hazard revised: Nature.com

[Ivan Seeking]

"Large meteorites are more likely to break up in the atmosphere before they hit the Earth than was previously thought, scientists in Britain and Russia have calculated."

http://www.nature.com/nsu/030714/030714-11.html

[I, Brian]

Great! Now we only need worry about the magnetic poles flipping!

[Andy]

I thought the Magnetic poles where supposed to flip every couple of milleniums anyway? Does anybody know what actually happened last time the Poles switched?

Does this mean that Compasses will be backwards after that? If so just think of how much money a compass maker could get just by swapping it around.

[I, Brian]

I was under the impression of having read something very recently in New Scientist, suggesting we're on a possible crux - the possibility of a reversal occuring over the next 1000 years. That's not a great span in terms of human history.

[Simfish]

What exactly would be the effects of a magnetic field reversal on humanity? I doubt that the effects would be clastrophobic because it has happened many times before; and mass extinctions don't seem to really have a link with magnetic field reversals. Of course, compasses will start to fail to work effectively, but we're finding better ways to find the direction of North; and the change is also gradual, so animals which rely on magnetism to navigate will have time to adapt..

How would the magnetosphere of the Earth change, for instance? Would we see the Auora Borealis at the Equator with a change, but not necessarily a reversal, in the magnetic fields? :P

[I, Brian]

What would be the effect of a magnetic field reversal?

Lost your satellites, for starters.

A field reversal will have a major impact on those societies most dependent upon electronics.

At least, that's the impression I'm under.