--------- #1265 - This Asteroid Missed Us, but, What If?
- Did you see it? On Monday, June 27, 2011, an asteroid flew by the Earth. It passed within 8,000 miles of us at 11:00 AM PDT. You may have missed it. Fortunately it missed us. This review is about the likely impact of a comet or asteroid making a direct hit.
- Attachments - asteroid
- The asteroid that flew by is called 2011MD. It was a rock 20 to 65 feet in diameter. Earth’s gravity significantly changed its orbit as it flew by. It circles the Sun and will be back in 2022. To see a computer animation of the flyby visit website:
------------- http://news.discovery.com/space/visualizing-asteroid-2011-md-zip-past-earth-animation-110624.htmi#mkcpgn=emnwsl
- What would have happened if the asteroid had hit the Earth?
- It would have been a spectacular fireball in the night sky but it would probably have exploded in the upper atmosphere. Small meteorites may have reached the surface. but, their impact is surprisingly common and not particularly harmful. Meteors are hitting the Earth’s atmosphere all the time. You can see them in the night sky as shooting stars.
- 2011 MD passed 11,000 miles from Earth’s center. Three other asteroids have been recorded passing closer than this. No doubt many asteroids much bigger have made close approaches without being detected. It is like looking for your car keys under the street light. We are just are now getting the technology to see out into wider circles.
- The asteroid 2011D had a peak brightness 11.0 Magnitude. The naked eye can detect brightness magnitudes of 6.0, so, you would need an 8 inch telescope to spot this asteroid as it flew in and passed by.
- In 2007 a small asteroid 7 feet in diameter plunged to the ground near the shore of Lake Titicaca in Peru. It exploded on land rather than up in the atmosphere. A huge dust cloud spilled a man off his bicycle and knocked a bull off its feet. The impact carved out a crater 40 feet in diameter.
- Asteroid 2008 TC was the size of an elephant. It broke up in the atmosphere and pieces landed in the desert in Sudan.
- All asteroids travel at similar speeds of about 60,000 miles per hour.
- The asteroid that hit 65,000,000 years ago was probably 9 miles in diameter. Its explosive force in the Yucatan Peninsula equaled 100,000,000 megatons of TNT. The impact result created the Cretaceous - Tertiary Boundary (K-T) in the evolution of life on the planet.
- The largest well documented asteroid impact occurred in 1908 near the Podkamennaya Tunguska River in Siberia. It was 130 feet wide with energy 30 million times less powerful than the K-T Boundary impact. The region was only sparsely inhabited and mostly forest trees suffered the impact for many miles around ground zero.
- Let’s say we manage to discover an asteroid heading our way. After several nights of observation astronomers can calculate if its orbit is in the path of Earth’s orbit. Let’s say their calculations are that it is 1.5 miles in diameter. That is about twice the size of the comet 103P/Hartley. Asteroids are solid rocks and metal so their trajectory can be accurately projected as a bullet. But, comets are more unpredictable because of their own outgassing. Their trajectories can change.
- Months of observation would identify this one as a comet and calculate its time and place of impact. What would we do? Lord only knows. I will let you speculate on the world’s reactions. There is a website that allows you to plug in the values and get a scenario of the expected damage around ground zero:
------------------------ www.purdue.edu/impactearth
---------------- 1.5 miles in diameter
--------------- 1,000 kilograms per meter^3, the density of ice
--------------- velocity 20 miles per second, 72,000 miles per hour.
- 50 miles from ground zero the fireball of the exploding comet would appear 60 times bigger than the Sun.
- Everything flammable would immediately burn up.
- A large earthquake would follow in 16 seconds.
- 4 minutes later an enormous air blast would hit with the wind speeds of 1,200 miles per hour.
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- If you were 300 miles away from ground zero you might survive, providing you seek shelter. You would see the fireball 2 times the size of the Sun
- The earthquake would occur 1.6 minutes after impact.
- The hurricane force winds (77mph) would hit 24.4 minutes after impact.
- Survival might be possible if people evacuated far enough away from impact, but, no one on the planet could avoid the disruption to the environment and to civilization in genreal. It would take years for the world to recover.
- The exploding comet would create chemical reactions in the atmosphere that would destroy the Earth’s protective ozone layer.
- An enormous electromagnetic pulse created in the explosion would disable electric grids and electronic equipment.
- Dust storms would block the Sun and cause substantial cooling.
- As temperatures drop the world’s food supply would be threatened.
- Then there is the reaction of civilization to such calamity. Would a civilized populace have the resilience to rebuild? Would there be political will to have prepared before hand? Would funding allow astronomers to search out and identify near earth orbit comets and asteroids months if not years before impact? Announcements will be made soon, stay tuned.
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707-536-3272, Wednesday, June 29, 2011
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