Quote from: Joelene9 on February 15, 2013, 03:13:04 PM
  There were two large meteor impacts in the 20Th century, both of them in Siberia.  The Tunguska Event over the Tunguska river in 1908.  This one completely blew up and vaporized about 4 miles up and yielded 10+ megatons of TNT, equivalent of a hydrogen bomb.  That flattened about 830 square miles of trees in a remote area.  This area was so remote and was at the end of the Romanov rule, WWI, and the beginning of the Soviet rule that it took until 1927 before an expedition to the area be commissioned. 
  The Sikhote-Alin meteor fall occurred over the Sikhote-Alin mountains in Eastern Siberia in 1947.  That one may be lighter in explosive yield than this recent one, but there was a large strewn field of iron meteorites from the Sikhote-Alin fall.  An iron-nickel meteor is more likely to strike the ground.  Meteor Crater, AZ is one of them. 

  Joelene

The Tunguska Event has always fascinated me and I love to watch documentaries that involve people going out to the area and filming it.  To see so many trees still lying down and hardly any growth...it's just fascinating. 

Quote from: Joelene9 on February 15, 2013, 03:13:04 PM
  There were two large meteor impacts in the 20Th century, both of them in Siberia.  The Tunguska Event over the Tunguska river in 1908.  This one completely blew up and vaporized about 4 miles up and yielded 10+ megatons of TNT, equivalent of a hydrogen bomb.  That flattened about 830 square miles of trees in a remote area.  This area was so remote and was at the end of the Romanov rule, WWI, and the beginning of the Soviet rule that it took until 1927 before an expedition to the area be commissioned. 
  The Sikhote-Alin meteor fall occurred over the Sikhote-Alin mountains in Eastern Siberia in 1947.  That one may be lighter in explosive yield than this recent one, but there was a large strewn field of iron meteorites from the Sikhote-Alin fall.  An iron-nickel meteor is more likely to strike the ground.  Meteor Crater, AZ is one of them. 

  Joelene

Joelene, have you heard of this one?

http://star.arm.ac.uk/impact-hazard/Brazil.html

http://en.m.wikipedia.org/wiki/List_of_impact_craters_on_Earth

Quote from: Devlyn Marie on February 15, 2013, 05:05:59 PM
http://en.m.wikipedia.org/wiki/List_of_impact_craters_on_Earth

You're feeding an obsession.   Impact craters are always fascinating to me. ^^

There's a triple somewhere, I believe in Missouri. The impactor broke up and left three craters in a perfect line. Small ones.

Quote from: Devlyn Marie on February 15, 2013, 05:17:49 PM
There's a triple somewhere, I believe in Missouri. The impactor broke up and left three craters in a perfect line. Small ones.

You're killing me.    I never knew about that in Missouri, but I never visited all that much over than to see the Mark Twain caves.

Quote from: Pleasingly Plump Jamie D on February 15, 2013, 02:36:52 AM
Meteorite hits Russia

http://rt.com/news/meteorite-crash-urals-chelyabinsk-283/

Airblast at about 38,000 feet.  Play the embedded video.

For a moment I thought you were talking about white, male, over-50, republicans....you know they seem to be going the way of the dinosaurs...LOL

Quote from: Pleasingly Plump Jamie D on February 15, 2013, 04:13:09 PM
Joelene, have you heard of this one?

http://star.arm.ac.uk/impact-hazard/Brazil.html

There have been many events, most of them in remote places.  More people are moving into these places that more reports of these will be more forthcoming.  The Earth has had a lot of impacts in the past, but the weathering makes it difficult to find these places.  The K-T event crater is covered by the Yucatan peninsula.  It took oil exploration coring in that area to accidentally find the mystery crater that decimated what was left of the dinosaurs. 
  On October 8, 2008 a large meteor broke up above the Nubian Desert in northern Sudan.  This was discovered as an asteroid 20 hours before it entered the atmosphere, the first discovery of a body that was predicted to hit the Earth.  This was discovered by Richard Kowalski of the Catalina Sky Survey (CSS) on Mount Lemmon north of Tuscon, AZ.  I do asteroid comfimations and I did some for the CSS, along with the usual suspects.  The fragments of that was found in the desert with the help of female science students wearing chadors from the University of Khartoum. 
  Eugene Shoemaker, a geologist who trained the Apollo astronauts, did search for signs of impacts all over the Earth.  He was also a co-discoverer with his wife Carolyn and comet hunter David Levy of the fragmented comet Shoemaker-Levy 9 that impacted in the upper atmosphere of Jupiter, giving it a series of black eyes that was visible for months through small telescopes.  He died in an auto accident in the Australian outback searching for more.
  Our Moon and Mercury does show the history of the bombardments.  Mars has some weathering by wind, but there are clues that the northern part of Mars was hit by a massive asteroid in the past due to the lack of old cratering.

  Joelene

Quote from: Pleasingly Plump Jamie D on February 15, 2013, 02:49:03 AM
Much of the video originates from the west Siberian city of Chelyabinsk, with a population of over 1,000,000.

Claims that Russian air defenses shot the meteor down are pure fantasy.  A fireball of this size was probably traveling 20 to 25 kilometers per second, or roughly 50,000 mile per hour, as it ablated.  (If I did my conversion correctly)

The meteor above western Siberia entered the Earth's atmosphere about 9:20 a.m. local time (10:20 p.m. EST Thursday) at a hypersonic speed of at least 33,000 mph (54,000 kph) and shattered into pieces about 30-50 kilometers (18 to 32 miles) high, the Russian Academy of Sciences said. NASA estimated its speed at about 40,000 mph, said it exploded about 12 to 15 miles high, released 300 to 500 kilotons of energy and left a trail 300 miles long.

Peky calculations from analyzing several videos: 10 mps = 36,000 mph

http://www.huffingtonpost.com/2013/02/15/meteorite-streaks-across-russian-urals_n_2691904.html

Russian Meteor Blast Bigger Than Thought, NASA Says

But late Friday, NASA revised its estimates on the size and power of the devastating meteor explosion. The meteor's size is now thought to be slightly larger — about 55 feet (17 m) wide — with the power of the blast estimate of about 500 kilotons, 30 kilotons higher than before, NASA officials said in a statement....

The meteor was also substantially more massive than thought as well. Initial estimated pegged the space rock's mass at about 7,000 tons. Scientists at NASA's Jet Propulsion Laboratory in Pasadena, Calif., now say the meteor weighed about 10,000 tons and was travelling 40,000 mph (64,373 km/h) when it exploded.

"These new estimates were generated using new data that had been collected by five additional infrasound stations located around the world - the first recording of the event being in Alaska, over 6,500 kilometers away from Chelyabinsk," JPL officials explained in the statement.

  The tiny pieces that were found so far has been classified as an ordinary L Chrondite, the most common type of meteorite to fall on the Earth.  This type have a iron nickel (Fe/Ni) composition of 7%-11%.  Chrondite, or "stonys" are the most common but are the hardest found due to the color and texture matches the rocks in our environment.  Most of the little fragments were found on the snow of the lake itself. 
  This Meteor has been officially called the Chebarkul meteor from the lake it fell in.  If this meteor had more iron in it, any settlements and everybody in those settlements between the city of Chelyabinsk and Lake Chebarkul would be toast due to the lower altitude the burst would occur.  The people of Chelyabinsk got lucky this time!  Chelyabinsk was a Soviet top secret city for nuclear research in the 50's.  In the nearby town of Kyshtym in 1957, a nuclear accident in one of the waste tanks was caused by a failure of the cooling system and a chemical explosion occured when the water in that tank evaporated to ammonium nitrate and acetates was set off by the heat of decay of the waste within.  This sent a main radioactive plume to the NNE, but away from Chelyabinsk.  Their first Chernobyl. 

  Joelene

There apparently was another "near miss" that was 3x the size that was only 17 000 miles from the surface. Not a planet killer, but we would have all felt it.

On related news, congress is still wanting to reduce NASA's budget.