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Showing posts with label Asteroid. Show all posts
Showing posts with label Asteroid. Show all posts

Saturday, February 16, 2013

Update on Chelyabinsk, Russia Meteor

The meteor that crashed near Chelyabinsk, Russia on Feb. 15, 2013 was about 50 now 55 feet in diameter when it entered the earth's atmosphere at an angle of 20 degrees to the horizon, moving at a speed of some 40,000 MPH and is estimated to have weighed 10,000 tons and delivered an explosive force of 300 now 500 kilotons of TNT, about 15x 25x the explosive force of the atomic bomb dropped on Nagasaki, ending WWII. It was about 1/3rd the size of mini-asteroid 2012 DA14 that coincidentally swept by the earth that same day at a distance of 17,200 miles. Although the chances of both coming so close to earth on the same day were minuscule, according to NASA the two were unrelated since the Chelyabinsk Meteor came from a completely different direction. Over 1,100 people were injured, mostly by breaking glass from the exploding fireball.

Orbits of asteroid 2012 DA14 and the Chelyabinsk Meteor. The Chelyabinsk Meteor was estimated at 15 feet in diameter (contrary to the caption here), weighing 10,000 tons, entering the earth's atmosphere from the direction of the sun in daylight. NASA has traced it's orbit back originating in the asteroid belt between Mars and Jupiter. Asteroid 2012 DA 14 was some 3x larger in size, comparable to the size of the Space Shuttle, and passed close by earth at a distance of 17,200 miles, between the ring of orbiting geosynchronous satellites and the surface of our planet.

It is not uncommon for stony meteors to explode in flight. The Chelyabinsk Meteor exploded into fragments at a height of about 12-15 miles, according to NASA. You can see and hear the explosion in many of the videos that were posted online.

Chelyabinsk is a large industrial city about 920 miles west of Moscow in the Ural Mountains. It is the location of one of only two plutonium processing plants in Russia whose output is used in making nuclear bombs. Had this meteorite struck during the cold war it could have mistakenly  triggered nuclear armageddon.

Comparison of different size meteors and the damage they can inflict. The Tunguska Event, also in Russia in 1908, destroyed 800 square miles of Siberian Forest. Had it fallen in a populated area it would have been an unparalleled disaster. The 10 kilometer asteroid that fell 65 million years ago in what is now Mexico was a planet killer, wiping out the dinosaurs and some 90% of the species then living.

As of this writing the only sign of the meteoroid on the ground is this 30 foot wide hole a fragment of it made in the ice covering Lake Chebarkul near the town of Chelyabinsk. The temperatures here get below 0 degrees Fahrenheit at night, so the ice is probably over 12 inches thick. So far Russian divers have found nothing in the lake, an unfortunate place for a large chunk to have landed since it will quickly become contaminated with debris from earth.

A thirty-foot hole in Lake Chebarkul marks the landing place of a fragment of the Chelyabinsk Meteorite.


Here is a terminological clarification:

Meteor: A streaking light in the sky, caused by a rock from space burning up as it enters the earth's atmosphere. Also called a "shooting star".
Meteoroid: The rock that burns up in the earth's atmosphere.
Meteorite: What a meteoroid is called when it strikes the earth, leaving pieces of itself behind.
Bolide: A meteor so bright that it can be seen in the daytime.
Fireball: Common name for a bolide.



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Friday, February 15, 2013

Asteroid 2012 DA14 Heading Toward Planet Earth

You've probably been reading about Asteroid 2012 DA14 which is headed for a close encounter with earth this Friday night, February 15th. DA14 is about 150 feet in diameter and will whiz by the earth at a distance of some 17,200 miles, within the ring of geosynchronous satellites that orbit the earth. Yes, this is a close call, but the asteroid will not strike the earth or any satellites in orbit around the earth. So, what will happen as it sails by? Nothing, nothing at all. Call it a close miss. But you will be able to observe this fast moving celestial body from Israel, starting at about 10:00PM local time and lasting through the early hours of Saturday morning.

The chart below shows the expected path of 2012 DA14 through the skies above Israel with time ticks representing Greenwich Mean Time. Add two hours to convert to Israeli local time.  Although it will move quickly compared to most celestial bodies because it is so close to earth, you will still not see it move at the speed of a plane or even satellite. As you can see from the chart, it will take over eight hours to go from the tail of Leo to the NorthStar. So, you will only be able to identify it by its motion if you watch for an extended period of time. You will also need binoculars since at a brightness between magnitude 7 and 8 it will not be a naked eye object.


Asteroid 2012 DA14's path through the skies above Israel. Timing ticks are in Greenwich Mean Time (GMT) so you will have to add two hours to find the asteroid's position in Israeli local time. It will shine between magnitude 7 and 8, so you will need binoculars or a telescope to see it.
If it's cloudy or you don't want the challenge of finding it outside, many observatories around the world will be live-streaming the event.  Israel's own Bareket Observatory is offering a free live webcast of the close approach on February 15 beginning at 10:15 Israeli local time, for a duration of about 3 hours. For more information, visit Baraket Observatory’s website. You’ll be automatically transfered to the live images, during the event.

NASA Television will provide commentary starting at 9:00PM Israeli local time on February 15. The commentary will be streamed live online at http://www.nasa.gov/ntv and http://www.ustream.tv/nasajpl2  

An object this size, thought to have a mass of 130,000 metric tons, would pack an explosive force of about 2.4 megatons of TNT if it struck the earth. The atomic bomb that leveled Hiroshima packed a blast of .02 megatons, so this asteroid could pack a wallop 120x as large as Little Boy. While not a planet killer, like the asteroid that struck the Yucatan Peninsula 65 million years ago and wiped out the dinosaurs, it is still something to be reckoned with. Fortunately, over 70% of the earth is water and there are still significant wilderness areas, so chances are it would strike an unpopulated area. Still it would be difficult to predict its actual strike zone, creating world-wide fear and uncertainty. This is the reason astronomers now scan nightly for Near Earth Objects (NEOs) in attempt to locate them before they strike the earth. The geological record shows that on average an "earth killer" asteroid strikes our planet every 50 million years. The last one was the Yucatan Peninsula strike some 65 million years ago, so we are about 15 million years overdue for extinction, in case you needed something else to worry about.

The last time an object this large struck the earth was the mysterious Tunguska Event of June 30, 1908, when a comet, some think asteroid, struck a remote region of Siberia and laid waste to a vast area of forest. Asteroids about 150 feet in diameter are thought to be about the size of the one that struck Arizona about 50,000 years ago, creating the great Meteor Crater which is 3/4 of a mile wide and 500 feet deep.



The orbit of asteroid 2012 DA14, shown looping within the orbits of the moon and the ring of geosynchronous satellites that orbit the earth. A close call!


Update: February 16, 2013

This video was taken by Francois Colas at Pic du Midi Observatory in France. It is a time lapse of 15 minutes of travel compressed into 16 seconds.





2012 DA14 2013 feb 15th Pic du Midi from Francois Colas on Vimeo.




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