Back to Home

XEphem Forum Message

Forums: Atm · Astrophotography · Blackholes · Blackholes2 · CCD · Celestron · Domes · Education
Eyepieces · Meade · Misc. · God and Science · SETI · Software · UFO · XEphem
RSS Button

Home | Discussion Forums | XEphem Ephemeris Software Discussion | Post
Login

Be the first pioneers to continue the Astronomy Discussions at our new Astronomy meeting place...
The Space and Astronomy Agora
Re: Severity Of Asteroid Impact

Forum List | Follow Ups | Post Message | Back to Thread Topics | In Response To
Posted by Malcolm McPherson/">Malcolm McPherson on December 13, 1999 03:05:34 UTC

It seems to me that it’s definitely the velocity of meteor impact that is the cause of all the trouble, because the energy it releases on impact is proportional to the velocity squared of the meteor. To illustrate this, here is yet another attempt (yawn!) to create a human-scale example of this interesting fact. If your Arizona meteor travelling at 40,000 mph had instead been an M&M (1 gram mass) that had miraculously descended, velocity undiminished, through a mysterious vacuum path to just the spot where I was blissfully standing, then that M&M would strike me with as much destructive energy as 1-ton (10e6 gram) Hyundai travelling at 40 mph. Why? Because the square of the velocity differential between the 1g M&M and the 10e6g Hyundai is 10e6 (one million), and KE=1/2mve2.

The Tanguska event of 1908 that you mentioned is a fascinating phenomenon. It seems to me that the destructive energy of the atmospheric explosion that flattened and burnt the area would have hit the trees in three successive ‘packages’. The first ‘package’ would be a flux of visible light and other high-energy radiation coming in at the speed of light (would this cause any damage?), then a second or two later the second package – an atmospheric shock wave - would arrive travelling at about 40,000 mph (which would flatten all the trees), and then the fireball would finally arrive to roast those fallen trees. It would have been much like an air-burst nuclear explosion, I would imagine. --------------------------------------------------

Your math seems sound enough. Indeed it is a good question. You already know that smaller meteors make big craters. The one in Arizona is almost a mile wide. It was caused by a meteor 60 feet wide at a speed of 40,000 mph! When meteors hit the earth with a large mass of pure iron on contact it literly vaporizes and causes a huge amount of friction and heat and a big hole. The energy released is astounding. The Arizona crater impact area is in a 40 mile radius! If a comet of 6 miles in diameter were to hit the earth, it would and probably will destroy almost all life. The earth itself can sustain hits like that easy. But when the energy is released in a confined atmosphere, weather patterns change drastically, dust particals from the comet will cover the sky. It could make a plume 5 miles or more in the sky. One good example of a non-impact meteor event was in Siberia in 1908. The meteor vaporized in the atmosphere before impact, but the energy released was enormous. It flattened trees for miles around. I probably didn't answer your question but there are some websites you can go to.

Follow Ups:

Login to Post
Additional Information
Google
 
Web www.astronomy.net
DayNightLine
About Astronomy Net | Advertise on Astronomy Net | Contact & Comments | Privacy Policy
Unless otherwise specified, web site content Copyright 1994-2017 John Huggins All Rights Reserved
Forum posts are Copyright their authors as specified in the heading above the post.
"dbHTML," "AstroGuide," "ASTRONOMY.NET" & "VA.NET"
are trademarks of John Huggins