cpdiii, you have a point but only because the paper was sorely misreported by Universe Today. From the very first sentence the actual paper maintains that we encountered a 100km comet that had been disintegrating for millennia before we crossed into a particularly lumpy and dangerous portion of the existing debris stream. The pre-existing fragments, large and small, impacted earth and exploded in the atmosphere. As you say, a 62 mile or 100km diameter object would hit the ground and ruin the earth completely before ever disintegrating in the atmosphere. As a (non-credentialed;) co-author of the papers, I have written to Universe and asked they correct this mistake. The same miscommunication on this point has dogged us for years. See the actual papers here on my blog, the Cosmic Tusk, and enjoy the incredible evidence behind our claims: https://cosmictusk.com/9483-2/
George A. Howard, Comet Research Group
Thank you very much for the clarification. This I can believe!
As an aside, when meteors explode in the atmosphere it is a function of stresses set up in the meteor by the intense heat on the surface and expansion on the outer layers and little expansion of the inner mass. This sets up tremendous stress in the stony meteors and they often explode. The iron-nickle ones simply ablate and if large enough make it to the surface. A 100k ice ball, rock or iron-nickle would arrive mostly intact and as said would be an extinction event. But it would be one hell of a fire works show for a few brief seconds. A lot of the fireworks would be very high intensity ultraviolet and cook you before impact.
Thanks again for the correction and you should rip a strip off the back of the editors at Universe Today. They served their publication poorly. I will read your article in its entirety.