APOD: Tunguska: The Largest Recent Impact... (2011 Oct 02)

Comments and questions about the APOD on the main view screen.
hee haw

Re: APOD: Tunguska: The Largest Recent Impact... (2011 Oct 0

Post by hee haw » Sun Oct 02, 2011 8:22 pm

orin stepanek wrote:Why wouldn't a comet entering the atmosphere be considered a meteor? If I see a streak of fire coming down; I doubt if I would think; hey; is that a comet of an asteroid coming down! I would probably hope I was out of harms way! :shock:
Look under the surface to find the answers. Classification is of what lands and is found, not what is seen.

meme

Re: APOD: Tunguska: The Largest Recent Impact... (2011 Oct 0

Post by meme » Sun Oct 02, 2011 8:26 pm

islader2 wrote:@ Dick Henry Writing dates in the format "year/month/date" is a very useful tool for accessing files--since only the last digit changes daily. Think about it--the US Army has. ThanX. :D :D
You know, I've advocated that for years, without realizing the fundamental reason for it in the computer age, which you bring out so well. Thank you!

User avatar
Chris Peterson
Abominable Snowman
Posts: 16174
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Tunguska: The Largest Recent Impact... (2011 Oct 0

Post by Chris Peterson » Sun Oct 02, 2011 8:48 pm

islader2 wrote:@ Dick Henry Writing dates in the format "year/month/date" is a very useful tool for accessing files--since only the last digit changes daily. Think about it--the US Army has. ThanX. :D :D
This big-endian notation is codified in ISO 8601. To take full advantage of it, however, it is important to use only numerals (no month names), and to always use leading zeros to force the day and month to be two characters. The result is an "alphabetical" date format, that will naturally sort with most file systems.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18443
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: Tunguska: The Largest Recent Impact... (2011 Oct 0

Post by neufer » Sun Oct 02, 2011 9:22 pm

hee haw wrote:
orin stepanek wrote:
Why wouldn't a comet entering the atmosphere be considered a meteor? If I see a streak of fire coming down; I doubt if I would think; hey; is that a comet of an asteroid coming down! I would probably hope I was out of harms way! :shock:
Look under the surface to find the answers. Classification is of what lands and is found, not what is seen.
That is not even a meteorwrong :!:
Chris Peterson wrote:
A meteoroid is the parent body (which could be of cometary material), either in space or in the atmosphere. The atmospheric phenomenon is a meteor. If a piece makes it to the ground, it is called a meteorite (although meteorwrongs are much more common <g>).
Art Neuendorffer

User avatar
orin stepanek
Plutopian
Posts: 6877
Joined: Wed Jul 27, 2005 3:41 pm
Location: Nebraska

Re: APOD: Tunguska: The Largest Recent Impact... (2011 Oct 0

Post by orin stepanek » Sun Oct 02, 2011 10:31 pm

hee haw wrote:
orin stepanek wrote:Why wouldn't a comet entering the atmosphere be considered a meteor? If I see a streak of fire coming down; I doubt if I would think; hey; is that a comet of an asteroid coming down! I would probably hope I was out of harms way! :shock:
Look under the surface to find the answers. Classification is of what lands and is found, not what is seen.
I would no get out of harms way for a meteorite as it has become mute. A meteror can still hurt you. :? 8-)
Orin

Smile today; tomorrow's another day!

Guest

Re: APOD: Tunguska: The Largest Recent Impact... (2011 Oct 0

Post by Guest » Mon Oct 03, 2011 1:52 am

I believe that there is just as much evidence that Tesla crated an inductive kick at a frequencey to bounce
off the ionisphere. No piece of a meteor or comet was ever found. Tesla had a huge tower with an antenna
on it and he was experimenting with broadcasting AC energy. He may have picked the most desolate place on earth
to aim his charge at. He and Edison were arguing over AC and DC. Tesla claimed that AC could be broadcast.
Edison said, "But where would we place the meter?"

The tower was torn down shortly after Tunguska so that no one else could use it.



Roger C. Gledhill

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18443
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: Tunguska: The Largest Recent Impact... (2011 Oct 0

Post by neufer » Mon Oct 03, 2011 1:56 am

orin stepanek wrote:
I would not get out of harms way for a meteorite as it has become mute. A meteor can still hurt you. :? 8-)
Speak for yourself, Orin.
http://en.wikipedia.org/wiki/Kryptonite wrote:
Image
<<Kryptonite is described as having formed through a process of nuclear fusion attendant to the explosion which destroyed the planet Krypton. Some accounts describe the fusion process as a result of the planet-destroying explosion, others as the cause of it, but all agree that the majority of the debris of the planet was converted into kryptonite and propelled into interstellar space by the force of the explosion, with some ultimately reaching Earth and becoming a threat to Superman—and other Kryptonians.

Kryptonite implies a meteorite from the planet Krypton, as in the Lois & Clark: The New Adventures of Superman episode "The Green, Green Glow of Home," where it is given as "periodic element 126", which in reality corresponds to unbihexium/eka-plutonium, the most stable of the elements in the so-called island of stability. Superman: The Man of Steel Sourcebook (1992), concurs, referring to kryptonite as "the common ore of the super-actinide kryptonium, an unusually stable transuranic element, whose atomic number is believed to be 126." Kryptonium is given a radioactive half-life of 250,000 years.

Some issues of Superman indicate the mechanism by which green kryptonite may hurt Superman. Superman's cells absorb electromagnetic radiation from stars (like Earth's sun). Kryptonite's radioactivity interferes with this semi-photosynthetic process, driving the energy out of his cells in a painful fashion. Some versions of the adverse effects of kryptonite describe the radiation as affecting the blood chemistry of the victim, causing accelerated effects similar to sickle cell anemia in terrestrial humans, and also causing the skin of the victim to turn green as exposure time increases.

Under standard chemical naming procedures, the -ite suffix of kryptonite would denote an oxyanion of the element krypton. However, krypton is a noble gas that forms compounds only with great difficulty, and such an oxyanion is not known. Nevertheless, the University of Leicester presented the Geological Society with krypton difluoride to commemorate the 70th anniversary of Superman.
>>
Art Neuendorffer

User avatar
Ann
4725 Å
Posts: 11562
Joined: Sat May 29, 2010 5:33 am

Re: APOD: Tunguska: The Largest Recent Impact... (2011 Oct 0

Post by Ann » Mon Oct 03, 2011 2:24 am

Image
Superman! Yeahh!



Ann
Color Commentator

User avatar
orin stepanek
Plutopian
Posts: 6877
Joined: Wed Jul 27, 2005 3:41 pm
Location: Nebraska

Re: APOD: Tunguska: The Largest Recent Impact... (2011 Oct 0

Post by orin stepanek » Mon Oct 03, 2011 2:38 am

neufer wrote:
orin stepanek wrote:
I would not get out of harms way for a meteorite as it has become mute. A meteor can still hurt you. :? 8-)
Speak for yourself, Orin.
http://en.wikipedia.org/wiki/Kryptonite wrote:
Image
<<Kryptonite is described as having formed through a process of nuclear fusion attendant to the explosion which destroyed the planet Krypton. Some accounts describe the fusion process as a result of the planet-destroying explosion, others as the cause of it, but all agree that the majority of the debris of the planet was converted into kryptonite and propelled into interstellar space by the force of the explosion, with some ultimately reaching Earth and becoming a threat to Superman—and other Kryptonians.

Kryptonite implies a meteorite from the planet Krypton, as in the Lois & Clark: The New Adventures of Superman episode "The Green, Green Glow of Home," where it is given as "periodic element 126", which in reality corresponds to unbihexium/eka-plutonium, the most stable of the elements in the so-called island of stability. Superman: The Man of Steel Sourcebook (1992), concurs, referring to kryptonite as "the common ore of the super-actinide kryptonium, an unusually stable transuranic element, whose atomic number is believed to be 126." Kryptonium is given a radioactive half-life of 250,000 years.

Some issues of Superman indicate the mechanism by which green kryptonite may hurt Superman. Superman's cells absorb electromagnetic radiation from stars (like Earth's sun). Kryptonite's radioactivity interferes with this semi-photosynthetic process, driving the energy out of his cells in a painful fashion. Some versions of the adverse effects of kryptonite describe the radiation as affecting the blood chemistry of the victim, causing accelerated effects similar to sickle cell anemia in terrestrial humans, and also causing the skin of the victim to turn green as exposure time increases.

Under standard chemical naming procedures, the -ite suffix of kryptonite would denote an oxyanion of the element krypton. However, krypton is a noble gas that forms compounds only with great difficulty, and such an oxyanion is not known. Nevertheless, the University of Leicester presented the Geological Society with krypton difluoride to commemorate the 70th anniversary of Superman.
>>
Wow! Superman is a older than I am! The first appearence was June 1938 in Action comic books. 8-) :mrgreen:
http://en.wikipedia.org/wiki/Superman_%28comic_book%29
Orin

Smile today; tomorrow's another day!

thongar
Ensign
Posts: 14
Joined: Fri Apr 17, 2009 2:29 pm

Re: APOD: Tunguska: The Largest Recent Impact... (2011 Oct 0

Post by thongar » Mon Oct 03, 2011 3:53 pm

I had heard somewhere (discovery Channel, or Sci Channel) about reports of a Arizona Meteor Crater size strike in the Amazon Basin in the 1930s, but it was so remote it was never confirmed. As I recall there now is Radar map coverage of evidence, Which is still in a remote area. If this is true would this not be a larger explosion than Tuguska?

Thongar

User avatar
Chris Peterson
Abominable Snowman
Posts: 16174
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Tunguska: The Largest Recent Impact... (2011 Oct 0

Post by Chris Peterson » Mon Oct 03, 2011 4:30 pm

thongar wrote:I had heard somewhere (discovery Channel, or Sci Channel) about reports of a Arizona Meteor Crater size strike in the Amazon Basin in the 1930s, but it was so remote it was never confirmed. As I recall there now is Radar map coverage of evidence, Which is still in a remote area. If this is true would this not be a larger explosion than Tuguska?
I don't think there is any evidence of an impact in the 1930s. The Iturralde structure in the Bolivian rainforest was identified by satellite imagery and radar, and may represent the Earth's youngest significant impact, at just a few tens of thousands of years.

The dynamics of an airburst and an actual ground impact are so different that comparing them (in the sense of "larger") is challenging, and certainly requires some careful explanation.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18443
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: Tunguska: The Largest Recent Impact... (2011 Oct 0

Post by neufer » Tue Oct 04, 2011 3:00 am

http://earthobservatory.nasa.gov/IOTD/view.php?id=52351 wrote:

<<Some meteor impact craters, like Barringer Crater in Arizona, are easily recognizable due to well-preserved forms and features on the landscape. Other impact structures, such as Bigach Impact Crater in northeastern Kazakhstan, are harder to recognize due to their age, modification by geologic processes, or even human alteration of the landscape.

At approximately five million years old, Bigach is a relatively young geologic feature. However, active tectonic processes in the region have caused movement of parts of the structure along faults, leading to a somewhat angular appearance (image center). The roughly circular rim of the 8-kilometer (diameter) structure is still discernable around the relatively flat interior. In addition to modification by faulting and erosion, the interior of the impact structure has also been used for agricultural activities, as indicated by the presence of tan, graded fields. Other rectangular agricultural fields are visible to the northeast and east. The closest settlement, Novopavlovka, is barely visible near the top of the image.>>
Art Neuendorffer

nicheo

Re: APOD: Tunguska: The Largest Recent Impact... (2011 Oct 0

Post by nicheo » Tue Oct 04, 2011 3:33 am

There is a theory that the explosion was man made http://home.comcast.net/%7Eonichelson/O ... NGUSKA.pdf
No one anywhere on earth reported seeing a large body falling to earth on that date.

Science Channel will have a segment about Tunguska on 10/5/11 http://science.discovery.com/videos/dar ... er-up.html

User avatar
Chris Peterson
Abominable Snowman
Posts: 16174
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Tunguska: The Largest Recent Impact... (2011 Oct 0

Post by Chris Peterson » Tue Oct 04, 2011 4:46 am

nicheo wrote:There is a theory that the explosion was man made http://home.comcast.net/%7Eonichelson/O ... NGUSKA.pdf
No one anywhere on earth reported seeing a large body falling to earth on that date.
That is not a theory. That is an absurd bit of fantasy, the product of some crackpot. There is no doubt at all that the Tunguska event was a natural phenomenon.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

Wolfgang Kundt

Re: APOD: Tunguska: The Largest Recent Impact... (2011 Oct 0

Post by Wolfgang Kundt » Fri Oct 07, 2011 11:03 am

Your APOD - according to a few insiders - does not describe "the Largest Recent Impact", but rather "the Largest Recent Outburst", for more than thirty independent reasons: we deal with a modern kimberlite. How can this more than a decade-old news be frequently suppressed ?!?

User avatar
Indigo_Sunrise
Science Officer
Posts: 438
Joined: Fri Jul 15, 2005 1:40 pm
Location: Md

Re: APOD: Tunguska: The Largest Recent Impact... (2011 Oct 0

Post by Indigo_Sunrise » Fri Oct 07, 2011 11:09 am

Wolfgang Kundt wrote:Your APOD - according to a few insiders - does not describe "the Largest Recent Impact", but rather "the Largest Recent Outburst", for more than thirty independent reasons: we deal with a modern kimberlite. How can this more than a decade-old news be frequently suppressed ?!?


I know I'll probably regret this, but:

WHAT?????

:?
Forget the box, just get outside.

User avatar
Chris Peterson
Abominable Snowman
Posts: 16174
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Tunguska: The Largest Recent Impact... (2011 Oct 0

Post by Chris Peterson » Fri Oct 07, 2011 2:30 pm

Indigo_Sunrise wrote:I know I'll probably regret this, but:

WHAT?????
The "insiders" he is referring to are all in an insane asylum... and not as staff!
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

Spaceball Wizard

Re: APOD: Tunguska: The Largest Recent Impact... (2011 Oct 0

Post by Spaceball Wizard » Mon Oct 10, 2011 8:04 am

Indigo_Sunrise wrote:
Wolfgang Kundt wrote:Your APOD - according to a few insiders - does not describe "the Largest Recent Impact", but rather "the Largest Recent Outburst", for more than thirty independent reasons: we deal with a modern kimberlite. How can this more than a decade-old news be frequently suppressed ?!?


I know I'll probably regret this, but:

WHAT?????

:?
What Wolfgang Kundt wants to say is that the impact model rises several issues which simply don't match the Tunguska event. Among the most important are a large fraction of eyewitnesses who describe a series of up to two dozens explosions lasting about 10 to 20 minutes, as well as a fireball that happily changed its flight direction. An impact or airburst would last only a few seconds (with a three-minutes delay between the fireball appearance and the arrival of the blast at Vanavara). According to http://esoads.eso.org/abs/2003ChJAS...3..545K a violent outburst of some 10 million tons of methane under high pressure out of an ancient volcano in this region could explain the scenario better than the airburst of a cosmic body. The methane outburst itself would be highly violent; even more violent, however, could be an explosive combustion of the methane-air mixture. Since methane has a smaller molecular weight than air, it rises upwards and may be easily ignited by high-altitude discharges (which can even be triggered by such events as many examples of volcanic lightning show). This flame would than travel back to the eruption site, like a burning fuse, possible along a zig-zag path due to high-altitude winds, and probably much slower than a meteorite. When it eventually reaches the bulk of the methane-air cloud, just 10% of the total methane amount need to be in an explosive mixture with the air to cause a 10 megaton equivalent explosion.

There have been several smaller events comparable, like e.g. the Cando event http://en.wikipedia.org/wiki/Cando_event, which have claimed to be gas outbursts rather than impacts.

The Spaceball Wizard

User avatar
Chris Peterson
Abominable Snowman
Posts: 16174
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Tunguska: The Largest Recent Impact... (2011 Oct 0

Post by Chris Peterson » Mon Oct 10, 2011 3:23 pm

Spaceball Wizard wrote:What Wolfgang Kundt wants to say is that the impact model rises several issues which simply don't match the Tunguska event...
Then that's what he should have said: that there is an old but serious reference that argues for an alternate explanation, and that while this probably doesn't describe the event at Tunguska, that possibility exists. Referring to "insiders" and "suppressed" information is a sure way to be taken as a crank.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18443
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

The Smallest Recent Comettes Impact

Post by neufer » Mon Oct 10, 2011 9:03 pm

http://www.universetoday.com/89750/a-meteorite-visits-the-comettes/#more-89750 wrote:
A Meteorite Visits the Comettes
by Jason Major on October 10, 2011 <<When your last name is Comette, I’m sure the occasional astronomy-themed joke is never far away. But it’s no joke that the Comette family living in Draveil, a suburb south of Paris, was paid a visit by a real extraterrestrial a couple of weeks ago – in the form of an 88-gram (3.5 oz.) meteorite that broke through their roof!

The Comettes were on vacation at the time, so didn’t realize their house had been struck by a space rock until they noticed a leak in the roof. When they called in a roofer it was discovered that a thick tile had been completely broken through.

The meteorite was found wedged in insulation.

Mineral scientist Alain Carion investigated the meteorite and determined that it’s an iron-rich chondrite, a 4.57-billion-year-old remnant of the early Solar System that most likely came from the main asteroid belt between the orbits of Mars and Jupiter. About 3/4 of all meteorites that have been observed landing on Earth are chondrites.

While obviously not impossible, the odds of your home being hit my a meteorite are incredibly slim. Only 145 meteorites have been documented landing in the US in the past 200 years. On March 26, 2003, just before midnight, hundreds of fragments of a large meteorite fell in the Park Forest area of Chicago. Several fell through roofs of houses and one punched a hole in the roof of the fire station. One large piece weighing about 2.5 kg crashed into a bedroom, narrowly missing a boy who was asleep in his bed! On September 23, 2003, a 20 kg stone meteorite tore straight through a two-storey house in New Orleans and came to rest in the basement. (Source: University of New Mexico Institute of Meteoritics.) Only about 50 meteorites have been found in France over the past four centuries, and none has ever before been discovered less than 80 km from Paris.

While they could attempt to sell the meteorite that struck their home, possibly fetching several hundred euros for it, the Comettes have decided to keep their otherworldly visitor. “A piece of the history of space of which we know nothing, but which is fascinating, has fallen on us,” Mrs. Comette told the Le Parisien newspaper. “It’s like a fairytale, and less likely than winning the lottery, we’re told.”>>
Art Neuendorffer

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18443
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Smiles all around as meteorite hits comet

Post by neufer » Mon Oct 17, 2011 9:27 pm

http://astrobob.areavoices.com/?blog=78068 wrote:
Smiles all around as meteorite hits comet
Posted on October 17, 2011 by astrobob <<OK, now that I’ve drawn you in to this story, here’s the truth. The meteorite didn’t hit exactly hit a comet but rather a ‘Comette’ as in the roof of a home owned by Madmoiselle Comette (pronounced the same) and her companion Monsieur Mosset in Draveil, a suburb of Paris. No one’s quite sure when the meteorite punctured the roof, but it may have happened in August while the couple was on vacation away from the city.

In early September their roof was leaking after a thunderstorm, so they called a roofer to make the repair. While replacing the roofing tiles, he discovered a curious black stone with a pale gray interior and presented it to the owners. Suspecting it might be a meteorite, Mosset later took the stone to the French meteorite collector Alain Carion who owns the Minerals-Fossils-Meteorites shop along the banks of the Seine River in Paris. Carion’s face must have lit up in a big smile, because it was clear to him that the 88g specimen was indeed a rock from space. In his own words: “Mr. Mosset did show me a splendid extra-terrestrial rock of 88 grams, with all the right features: black fusion crust, regmaglypts , pale matrix inside with traces of iron and troilite, attracted to a magnet. Perfect! We had here a real meteorite, and fallen just outside Paris.” Just an FYI, regmaglypts are those thumbprint shaped depressions seen in some meteorites. They’re places where the heat of entering Earth’s atmosphere has melted out softer materials in the stone.

To the delight of everyone, two additional pieces weighing around 2 and 5.3 kilograms of the meteorite fall have recently been found. Since no known meteorite has ever fallen so near Paris, meteorite collectors around the world are very excited about the possibility of adding a small fragment of history to their collections. From outward appearances, the meteorite looks like an what’s known as an ordinary chondrite. Chondrites are extremely ancient – 4.5 billion years old – and thought to originate in the crusts of asteroids in the asteroid belt. Collisions between asteroids liberate fragments which eventually find their way to Earth and lovely places like Paris.
Art Neuendorffer