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Introducing Asteroid 2004 MN4
Numerous readers wrote in with bits about a potential asteroid collision: "The recently discovered asteroid 2004 MN4 is currently listed as having a 1/233 chance of hitting the Earth. It is 420 m across and if it strikes the Earth it will release an energy of 1,900 Megatons of TNT (the largest nuclear weapon ever detonated, Tsar Bomba had a yield of only 50 Megatons). It is also the only asteroid that currently has a Torino scale value of 2." So, in summary, there's a 1-in-233 chance of the worst disaster in recorded history happening on April 13, 2029, and a 232-in-233 chance of nothing happening. Have a nice day! Update: 12/24 22:14 GMT by M : The rock is now rated a 4 on the Torino scale, or a 1-in-62 chance of impact.
If we start now, we have 24 years to figgure out how to deflect it's orbit. If it's not on a collision course after all, then we still have learned how to deflect a large asteroid.
"maybe they boil off a significant part of the oceans as they cool down"
Why maybe when all the numbers are available online? Ten million megaton of TNT equivalent of energy is enough energy to vaporize 2 x 10^16 kg water. The Atlantic Ocean by itself has 3 x 10^20 kg of water. That is about 1 part in 10,000 of just the second largest ocean.
That's a lot of water but a very small fraction of the total.
Asteroid 2004 MN4 is a 440m diameter, ~3500kg/m^3 (unless I've got my maths wrong), 12.59km/s impact velocity asteroid. Impacting on a 45? angle on a continental shelf, at 100km away buildings would shake, glass windows would shatter, chimneys shanty towns would collapse, ejecta would arrive in scattered fragments.
At 10km away, everything gets blown up by the earthquake, ejecta and blast wave. So, if it DOES hit, you'll probably be ok unless you happen to live close to the impact site.
I ran the calculation at the same site, but using the size of the one we're supposedly talking about, porous rock instead of dense rock or iron, and I dropped it into the mid-Atlantic, the earth being 74% covered by water after all.
It broke up, there was no fireball, and I could make more impact overpressure (I chose to be 1,800 km from the impact site) by clapping my hands real hard.
Then again, an impact like "mine" happens every 4,000 years or so.
"Ain't no right way to do a wrong thing."