[mike]

mike asked the Naked Scientists:
   
Love your podcasts !!

I was wondering what the short and long term difference would be if a
significant (ie dinosaur killing) meteor/asteroid were to impact earth in

1- land mass
2- deep ocean
3- polar ice cap

It would seam that each would have different materials ejected, displaced, etc.

Would one of them be "better" than the others ?

thank you for your brilliant show.

What do you think?

[Vern]

I'll make some guesses; maybe someone better at guessing than I can do better[]

An object the size of the dinosaur killer if it hit land would send massive amounts of debris and gaseous rock into the atmosphere. The larger particles would rain down as fiery hot meteors setting ablaze most of the forests. The gasses and dust would linger in the atmosphere for months, blocking the sun and creating year round winter that may last for several years.

If such an object hit in mile-deep water, it would have much the same effect, but in addition there would be a mile-high tsunami that would oscillate around the world a few times. Mountain ranges would get build-ups and wash backs that would give coastal areas a double hit. 

If it hit the polar ice cap, I see the same effect as if it hit on land. There would just be more water in the upper atmosphere, so maybe lots of rain. Still there would be the cloud-caused winter.
     

[LeeE]

I'd be inclined to agree with Vern; it's reckoned that the Chicxulub bolide was at least 6 miles in diameter, so one mile deep water isn't going to make much difference to the impact, apart from adding the immense tsunami.  In that case then, I guess it'd be better if it fell on land.