What's more elastic, dirt or water?

[CharlieNNC]

Thinking about the effects the earthquake in South America had on earth parameters, I pondered the theorized impact of the asteroid that hit what is now the Gulf of Mexico region, with it's most visible proof theorized being the extinction of the dinosaurs, and the worldwide layer of (forgot the minerals name) at the same depth everywhere. With that impact, assuming it would be a bit more catastrophic that the earthquake in question, is there any theory as to it effecting earth rotational speed? How about driving it's orbit closer to the sun? And why do these things seem to be assumed that they hit the earth in a 90 degree angle, and not a glancing re-entry. To my subject question. I was interested when the Myth Busters did the segment where one of their myth required them to fire bullets into water. Any supersonic speed bullet shattered on impact with the water, with a rain of metal fragments drifting downward. Top speed was on the order of 3000 feet per second. An asteroid or meteorite traveling at 10's of thousands of miles per hour and hitting the water, would not it shatter to pebbles almost on contact, and generating a wave that would be proportionally smaller? Back to the bullet. One fired into dirt will cause an impact crater and impact like ejecta, but it can be dug out of the dirt in fairly intact shape if a full metal jacket round. While being a pointed object might explain the bullets intactness in dirt, it apparently has no benefit in impacting water. A cliff diver is a variable though. While he can protect his head between his out stretched arms, and form his hands into fists to punch a hole in water and survive, that will not work with dirt. Anybody fired any rocks at water at supersonic speeds?

[rstevenson]

It looks like you had a large question which kind of shattered on impact into this spray of related questions.

There's a lot of information about the Chicxulub crater in Wikipedia. Also in Wiki is this Impact event article, with more general information.

No, the Chicxulub event was not nearly big enough to have more than a miniscule effect on the Earth's orbit. And it didn't necessarily "hit the earth in a 90 degree angle". Near-circular craters can be produced by angles of impact a lot less than 90°.

The impact of such a large rock cannot be understood in comparison with firing a bullet into water or dirt. It's a lot more complex than that, involving atmospheric compression ahead of the meteor, immense heat, and other effects which don't occur with mere bullets.

Rob

[neufer]

While you are at it, you might also wish to contemplate Chicxulub Crater's possible "little sister": Tycho Crater on the Moon. It was caused by a ~5 km in diameter meteor (~8.1 times less massive than the one that killed the dinosaurs) which hit the moon (~81 times less massive than the earth) about 108 million years ago (Mya). It's relative physical impact would have been about 10 times greater.

<<Tycho (86 km in diameter) is a relatively young crater, with an estimated age of 108 million years (Mya), based on analysis of samples of the crater rays recovered during the Apollo 17 mission. This age suggests that the impactor may have been a member of the Baptistina family of asteroids, but as the composition of the impactor is unknown this is currently conjecture. However, simulation studies give a 70 percent probability that the crater was created by a fragment from the same break-up that created asteroid 298 Baptistina; a larger asteroid from the same family may have been the impactor responsible for creating Chicxulub Crater (180 km in diameter) on Earth 65 million years ago (Mya), and causing the extinction of the dinosaurs.>>

[bystander]

http://asterisk.apod.com/viewtopic.php?t=6600
http://asterisk.apod.com/viewtopic.php?t=15386
http://asterisk.apod.com/viewtopic.php?t=21787