Recently scientists all over the world have presented many models describing a collision of the Earth with an asteroid or a comet. All of us can imagine the consequences of such a collision. That is a powerful impact wave, a huge tsunami from the body falling into the ocean and the so-called “impact” winter and “firey” rain consisting of material from the Earth’s crust blasted to the edge of the atmosphere with a subsequent rain of meteors back to the Earth. All these scenarios are possible with the falling of a large body similar to that which possibly killed off the dinosaurs at the Cretaceous-Tertiary boundary (the so-called K-T Event).
Is this all we can expect from such a catastrophic scenario? Or do we need to prepare for something more? As studies by the American scientists of the Planetary Science Institute (PSI) have shown, one more biosphere-destroying event will be the destruction of the planet’s ozone layer. The group, under the direction of Elizabeth Pierazzo, generated two models describing the fall of asteroids 500 and 1000 meters in diameter into the ocean (depth of 4000 meters). From their analysis of the data the scientists came to some conclusions about the catastrophic consequences of the ejection of huge quantities of hot water vapor into the atmosphere. After the water vapor, the liberation of huge volumes of chlorides and bromides will continue the process of destroying the ozone layer. As a result of these events, there will be a global exhaustion of the ozone layer, and Earth life will be defenseless for years.
The UVI (ultraviolet index) may be over 20 for several months after Earth is hit by a 500 meter asteroid. A reading of 10 is dangerous to humans, and 20 is the maximum value ever recorded on Earth. Under such radiation, a person can get burned even after only five minutes in the sun. Even more serious are the facts associated with the impact of a kilometer-sized asteroid. The brightness of the ultraviolet radiation will reach a huge value – 56! A person without protection in the open sunlight would literally burn up. The ultraviolet intensity would gradually decrease, but over the course of two years its level would remain over 20.
During this time most of the plant and animal life on Earth would perish; in countries where there are not huge reserves of foodstuffs, hunger would become a problem. All this is without calculating in the catastrophe which a huge tsunami would cause.
All these data are not to scare the people of the Earth, but, instead, they have the purpose of bringing understanding of what we must be prepared for, if we want to preserve our civilization at our modern level of development, and not plunge it into chaos because we couldn’t take a hit from space.
COMMENTARY: In a blog post dated June 25, 2011, I told you about near Earth object 2005 YU55, an astroid that is scheduled to come very close to Earth on November 8, 2011. If it stays on its projected course, 2005 YU55 will pass between the Earth and the Moon. That's close and scary.
Discovered December 28, 2005 by Robert McMillan of the Spacewatch Program near Tucson Arizona, the asteroid has been previously observed by Mike Nolan, Ellen Howell and colleagues with the Arecibo radar on April 19-21, 2010 and shown to be a very dark, nearly spherical object 400 meters in diameter. Because of its approximate 20-hour rotation period, ideal radar observations should include tracks that are 8 hours or longer on multiple dates at Goldstone (November 3-11) and when the object enters Arecibo's observing window on November 8th.
Using the Goldstone radar operating in a relatively new "chirp" mode, the November 2011 radar opportunity could result in a shape model reconstruction with a resolution of as fine as 4 meters. Several days of high resolution imaging (about 7.5 meters) are also planned at Arecibo. As well as aiding the interpretation of the radar observations, collaborative visual and near infrared observations could define the object's rotation characteristics and provide constraints upon the nature of the object's surface roughness and mineral composition.
Since the asteroid will approach the Earth from the sunward direction, it will be a daylight object until the time of closest approach. The best time for new ground-based optical and infrared observations will be late in the day on November 8, after 21:00 hours UT from the eastern Atlantic and western Africa zone. A few hours after its close Earth approach, it will become generally accessible for optical and near-IR observations but will provide a challenging target because of its rapid motion across the sky.
According to NASA astronomers, 2005 YU55 will come within .85 lunar distances or approximately 200,000 miles from the Earth. NASA is naturally concerned with Astroid 2005 YU55, but claims it will not impact Earth. However, Russian astronomers are not so sure, claiming that there is a very high probability that it could impact Earth.
If Astroid 2005 YU55 has been estimated to be 400 meters in diameter or roughly 1,100 feet (the size of a U.S. Navy supercarrier or height of the Empire State Building). However, an impact with Earth may be quite catastrophic, depending on whether it is a rock or iron asteroid. A rock asteroid will probably breakup as it enters Earth's atmosphere. An iron asteroid (the most common) could impact with great force.
The size of 2005 YU55 makes it particularly dangerous. If it hit a populated area on Earth, the resulting explosion would have the force of several nuclear bombs. And if it hit the moon, it could push our satellite off orbit with potentially disastrous results for the tides on Earth. In other words, we should be very glad that 2005 YU55 is going to miss us, and we should be more prepared for the inevitable time when a similar asteroid isn’t so accommodating.
In my blog post dated June 25, 2011, you will find that as of March 2011, a total of 8,000 near-Earth objects have been discovered. Thankfully, Astroid 2005 YU55 is the only near-Earth object that presents real danger if it should impact earth. However, these facts should not give us any comfort. There is always the possibility that a near-Earth object may not be detected in time to warn humans on Earth.
To give you an idea of just how many near-Earth object there are within close proximity to Earth, just look at this video, which shows the projectories of these near-Earth objects in relation to Earth. As you can see, it's like an astronomical "soup" or cosmic freeway out there, with Earth like a predestrian dodging traffic.
If this blog post did not scare you, please read my comet Elenin post just prior to this one. I can almost guarantee that you will be scared silly, but you have nearly two full days to make necessary plans. Nighty-night.
Courtesy of an article dated October 28, 2010 appearing in SpaceObs.org and an article dated July 27, 2011 appearing in 100GF
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