Posted on 01/10/2007 8:28:03 PM PST by PioneerDrive
Friday the 13th of April 2029 could be a very unlucky day for planet Earth. At 4:36 am Greenwich Mean Time, a 25-million-ton, 820-ft.-wide asteroid called 99942 Apophis will slice across the orbit of the moon and barrel toward Earth at more than 28,000 mph. The huge pockmarked rock, two-thirds the size of Devils Tower in Wyoming, will pack the energy of 65,000 Hiroshima bombs -- enough to wipe out a small country or kick up an 800-ft. tsunami.
On this day, however, Apophis is not expected to live up to its namesake, the ancient Egyptian god of darkness and destruction. Scientists are 99.7 percent certain it will pass at a distance of 18,800 to 20,800 miles. In astronomical terms, 20,000 miles is a mere stone's throw, shorter than a round-trip flight from New York to Melbourne, Australia, and well inside the orbits of Earth's many geosynchronous communications satellites. For a couple of hours after dusk, people in Europe, Africa and western Asia will see what looks like a medium-bright star creeping westward through the constellation of Cancer, making Apophis the first asteroid in human history to be clearly visible to the naked eye. And then it will be gone, having vanished into the dark vastness of space. We will have dodged a cosmic bullet.
Maybe. Scientists calculate that if Apophis passes at a distance of exactly 18,893 miles, it will go through a "gravitational keyhole." This small region in space -- only about a half mile wide, or twice the diameter of the asteroid itself -- is where Earth's gravity would perturb Apophis in just the wrong way, causing it to enter an orbit seven-sixths as long as Earth's.
(Excerpt) Read more at men.msn.com ...
Well, it's not Good Friday in 2029--that comes two weeks earlier on March 30.
Perhaps this phenomenon is part of why we haven't made contact with another planetary race. I don't think it was possible for the Drake equation to take this into consideration, was it?
I plan to be out of town then .....
Yikes! Looks like I'll be prayin' extra hard during Lent season that year (assuming I'm still alive)...;)
I've heard of this Apophis. Col. Jack O'Neill kicked his butt!
Could anyone explain to me how the impact of a 25-million-ton, 820-ft.-wide asteroid traveling at 28,000 mph would only generate an 800-ft. tsunami (assuming it hit the ocean)? Those numbers seem a bit off to me.
I'd guess it might be due to a fairly large amount of water at any ocean impact site being superheated, and therefore no longer liquid.
So, factor in your own ratio to your enumerated Drake equation, along with numerous others that are distinct possibilties as well.
The energy at impact has to be absorbed. Since it can't be done instantly, the result is a wall of water.
Sure puts a sharp edge to "now is the acceptable time..."
800 ft is plenty big.
It would be a good time to land a colony of humans and hitch a ride out of the solar system.
Considering that it would be moving at several hundred miles per hour, I'd say so. I recall a computer simulation of an impact in the Atlantic off the coast of Florida showed inundation well north of St. Louis, following the Mississippi River valley, in less than five hours' time.
Some velocity (probably very little) would be scrubbed off in the atmosphere.
Some would be picked up by falling into the gravity well.
Lose some kinetic energy (mass) by burning off in the atmosphere.
Then upon impact, a lot of energy goes to heat - vaporizing water and rock (ocean floor).
Some energy goes to displacing water, but that would be minimal. It wouldn't so much displace water as vaporize anything in its way. The water simply could not get out of the way fast enough - you couldn't accelerate it laterally fast enough. It would probably drive a water column down into the ocean floor.
The real tsunami generator would be the water rushing back in to the hole blown in the ocean floor and into the column of vaporized water.
Don't tell that to Seth Shostak.
Remember, if it's really omly a missile,, ya gotta let it it.
I wonder how much water would be vaporized; could the energy generate a nuclear detonation; would the energy split the tectonic plate and set off a slippage? So many questions, so little knowledge.
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