Prehistoric meteor shower? |
Prehistoric meteor shower? |
Dec 13 2007, 07:02 PM
Post
#1
|
|
Member Group: Members Posts: 688 Joined: 20-April 05 From: Sweden Member No.: 273 |
A real weird news story from Nature about meteor damage to pleistocene fossils:
http://www.nature.com/news/2007/071212/ful...s.2007.372.html If traces of this meteor shower has been found in both Siberia and Alaska as the story implies, then multiple impactors must have been involved. Such small meterites would lose speed quickly so the airburst must have occurred at fairly low altitude. |
|
|
Dec 19 2007, 02:45 PM
Post
#2
|
|
Member Group: Members Posts: 656 Joined: 20-April 05 From: League City, Texas Member No.: 285 |
I wonder whether this may have more to do with the mammoth using their tusks to dig in the ground (as I seem to recall that modern elephants do) and in the process embedding the metal fragments from a meteorite which just happened to be buried in the soil. In this case the "burn marks" may simply be oxidation rings and/or due to inflammation around the embedded fragments. This may also correlate with the dorsal distribution of the fragments - I would envision the mammoth pushing the tusks into the ground, then lifting. The same explanation works for the bison horns. I'm having a really tough time accepting them as due to the impact event, as any event which yields small particles moving fast enough to do this would likely also be throwing out a lot of big rocks and heat, and the bigger rocks would travel further than the small particles.
|
|
|
Dec 19 2007, 03:34 PM
Post
#3
|
|
Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
|
|
|
Dec 19 2007, 04:17 PM
Post
#4
|
|
Member Group: Members Posts: 656 Joined: 20-April 05 From: League City, Texas Member No.: 285 |
Maybe not if they are fallout from a mushroom cloud. And my assumption was that all the particle sizes would have begun with the same velocity, and thus the smaller particles would be decelerated by the air faster than the larger ones. The opposite is also true, that the smaller particles would be accelerated more than the larger particles by an expanding volume of gas. I could believe the impact hypothesis more easily in the context of your notion of fallout from a mushroom cloud (or secondary impact) if I could be persuaded that the terminal velocity of particles of this size would be sufficient to embed them within the tusks. This falls under the old "if you drop a penny from the top of the Empire State Building" question, or alternatively the "if you shoot a bullet straight up into the air and it falls back" question. Seems like Mythbusters addressed this and found that falling bullets or pennies would hurt (like paintballs) but not cause serious injury. |
|
|
Lo-Fi Version | Time is now: 13th June 2024 - 10:33 AM |
RULES AND GUIDELINES Please read the Forum Rules and Guidelines before posting. IMAGE COPYRIGHT |
OPINIONS AND MODERATION Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators. |
SUPPORT THE FORUM Unmannedspaceflight.com is funded by the Planetary Society. Please consider supporting our work and many other projects by donating to the Society or becoming a member. |