APOD: Tunguska: The Largest Recent Impact ... (2007 Nov 14)

[Bateleur]

http://apod.nasa.gov/apod/ap071114.html

I find this photograph rather strange, and a little suspicious.

Apparently it was taken 20 years after the event.

But there's no new re-growth. Why haven't the stripped trees developed new leaves and branches? Why isn't there new underbrush springing up to cover the fallen trunks?

Think how quickly plants started to re-colonise the devastation around Mount St Helens. What was that like, 20 years after the eruption? Pretty well vegetated, wasn't it?

Any thoughts on this?

[craterchains]

Don't question ! ! !

No conspiracy theories allowed ! ! !

Accept what "they" tell you.

Just my advice when it comes to APOD, so called, discussion forums.

[herbraab]

There is regrowth. For example, on the far right in the image, there are a few small, newly grown trees.

Don't forget, this is not Washington, this is Siberia. I have seen slices from trees from the Tungsuka impact site, and the annual rings are extremely narrow. Plant growth is very slow there.

Cheers, Herbert

[Dr. Skeptic]

That is true, there is new growth visible. I've examined trees in at similar latitude in Canada and have seen trees between 1cm and 2cm in diameter and 2 meters tall that were between 100 and 120 years old. (in bad growing conditions)

It is also a winter picture when there is no short flora to better document the damage.

[orin stepanek]

http://antwrp.gsfc.nasa.gov/apod/ap071114.html
Kind of stark appearing! Good thing it happened in the wilderness.
Orin

[TimeTravel123456789]

I just checked the local Chicago Public Library catalog and there are a few books on the topic. I will check out one or two out today.

I am interested in the direction of the tree fall down. Is it consistent with Lake Cheko's location?

Why would say that some trees are standing?

I appreciate the image and the comments. Wonder if an early Vygotsky or one of the early rocket scientists from Russia may have been fooling around?

[auroradude]

I also might point out that travel in this type of terrain is very difficult and impossible at some times of the year.

Because of the permafrost, the ground only thaws towards the surface in the summer and the water cannot seep down into it so it forms swamps or muskegs. This is also why the trees grow slowly. They cannot form a good root structure. The Russians call this type of forest "taiga" meaning little sticks or dwarf trees.

The best time to travel this terrain by foot is in the late fall when the ground is completely frozen but the snow is not too deep yet. The photo looks like it could have been taken at this time of year so that all the green summer growth is no longer present. Leaves are gone (willow, birch, alder) and grass or ferns are dead and fallen. This leaves the young spruce trees at the right of the photo as the best evidence for re-growth.

The image might also have been taken in the mid spring when snow is starting to disappear in the day but still freezes at night. Again, the vegitation has not started its annual growth cycle. If the photo had been taken in July it might look very different.

[iamlucky13]

Lake Cheko is a couple miles away from the epicenter of the explosion, as determined by the treefall pattern which was mapped out carefully during the original expedition. The fragment thought hypothetically to have dug Lake Cheko would have been coming in at an angle, accounting for the offset.

By the way, even the temperate forest land around Mt. St. Helens took some time to get re-established. Here's a picture from five years later:



And some areas regrew much more slowly. A lot of the greenest stuff you see today is Weyehauser forest land that was replanted shortly after the eruption. A 1997 picture and a 2007 picture (note wispy steam in the crater rising from the currently ongoing eruption) from Johnston Ridge:

[auroradude]

And if I had just read the link to the "Russian expedition" here; http://www.unmuseum.org/kulik.htm I would have learned that the expedition did indeed start in April to avoid the time when the area would turn into a complete swamp and the thick swarms of misquitos that would follow. Upon the arrival, the expedition noted that snow was still on the hills so this is indeed a time of year when green vegetation, other than the young evergreens, is not yet present.

[kankel]

The caption on APOD today http://antwrp.gsfc.nasa.gov/apod/astropix.html indicates that the Tunguska event was the largest recent natural explosion. The eruption of Mount Krakatoa, for example (1883) was at least 10 times bigger --- 200 megatons! /http://en.wikipedia.org/wiki/Krakatoa]

[BMAONE23]

I guess that the truth of the image depends on what story you read.
This link indicates that the image was taken on an expedition about 20 years later approx 1928.

This link however indicates that the (SAME?) image was taken in 1953, 45 years after the event.

[auroradude]

And don't forget the explosion of Nova Erupta at Katmai (Alaska) in 1912. It was estimated to displace twice as much material as the Krakatoa eruption with some 240 megatons worth of energy.
Perhaps "largest recent explosion on Earth with extra-terrestrial origins" would be more appropriate.

[Wadsworth]

Any way you put it, it's awesome.
And I’ll admit, slightly alarming.

[Jeebo]

The APOD caption says it was a meteor, but I remember watching Cosmos when Carl Sagan was talking about it, and he said it was a piece of a comet. He even named the comet, but I don't remember the name now.

Ron

[kovil]

In searching for some recent pictures of Tunguska this arrived.


http://www.thunderbolts.info/tpod/2006/ ... nguska.htm

http://www.thunderbolts.info/tpod/2006/ ... guska2.htm

It's a good read and worthy of consideration, as heinously disallowed as APOD regards it notwithstanding. (Norman Mailer, bless your linguistic adventurous fearlessness)

[JohnD]

Well, the area has certainly grown back now.
Google for "Tunguska map" and find several - different! - Google maps that purport to show the site of the explosion. Even a tourist guide to the area, that combines accurate description with red-top speculation!
http://www.sibtourguide.com/tunguska.html

Several Google map show such a large, round feature that it must be the fall site. Not! I fear that it was chosen as 'typical', though such a structure couild not have been missed by the explorers.
http://www.satellite-sightseer.com/id/4 ... uska_Event

But this must be the most extensive site: http://www.tunguska.ru/sitemap_en.htm
This index page is in English, but the rest of the site is in Russian.
It includes many modern as well as contemporary photos, and a page of a satellite shot of the same area with lots of 'pop-up' pictures:
http://tunguska.ru/travel/
This has the same round structure as above. So I must be wrong about that.
Anyway, enjoy!

John

[iamlucky13]

I guess that the truth of the image depends on what story you read.
This link indicates that the image was taken on an expedition about 20 years later approx 1928.
This link however indicates that the (SAME?) image was taken in 1953, 45 years after the event.

I've seen that photo attributed to Kulik's expedition in 1928 in several different locations. I suspect the National Geographic article is in error. Perhaps they got it from an archive that was indexed in 1953 or something?

The APOD caption says it was a meteor, but I remember watching Cosmos when Carl Sagan was talking about it, and he said it was a piece of a comet. He even named the comet, but I don't remember the name now.

He was probably talking about this.

[ReallyFUBAR]

Sagan is right, it was a comet. If you think about it, comets are just "dirty snow balls",and this was a steam explosion. Think about velocities, mass, composition, and...rate of explosion. Unless anyone can think of any other way to explain the stripped trees under the focus, and the fallen trees around the incident. It got very hot, broke up, and exponentionally increased it's surface area, poof! Is it possible it produced a large fast ball of expanding gas that did the damage? Steam power is thought to be obsolete, but it can do enormous work.. especially if the heat and mass is large enough...

[Chris Peterson]

The APOD caption says it was a meteor, but I remember watching Cosmos when Carl Sagan was talking about it, and he said it was a piece of a comet. He even named the comet, but I don't remember the name now.

A meteor is the energetic release of energy in the atmosphere by a high velocity object from space. That object can be asteroidal, cometary, or by most definitions, man-made space junk.

Sagan is right, it was a comet. If you think about it, comets are just "dirty snow balls",and this was a steam explosion. Think about velocities, mass, composition, and...rate of explosion. Unless anyone can think of any other way to explain the stripped trees under the focus, and the fallen trees around the incident. It got very hot, broke up, and exponentionally increased it's surface area, poof! Is it possible it produced a large fast ball of expanding gas that did the damage? Steam power is thought to be obsolete, but it can do enormous work.. especially if the heat and mass is large enough...

It is unknown what kind of object was involved. You underestimate the amount of energy released when an object breaks apart in the atmosphere at a hypersonic speed. The Tunkuska event could very easily have been the product of a stony meteoroid. Even the "dirty snowball" model of comets has been challenged lately, as it increasingly appears that comets may be more like "snowy dirtballs".

[FieryIce]

It looks like the majority have missed the information about the Tunguska explosion from a Dr. Valery Uvarov, of Russia's National Security Academy, a 5 part article starting with part 1 an interview.

But then again, I am not surprised

The Installation, An Interview with Valery Uvarov. Interview
Mysteries of Siberia's "Valley of Death" Part one
Mysteries of Siberia's "Valley of Death" Part two
Mysteries of Siberia's "Valley of Death" Part three
Mysteries of Siberia's "Valley of Death" Part four


The direction of the fallen tree trunks at the epicentre of the explosion.


"Diagram from the periodical Tekhnika i Molodezh (no. 1, 1984), showing the location of witnesses and the trajectories of "terminator spheres" taken for the meteorite as reported to researchers Suslov (1), Astapovich (2), Krinov (3), Konenkin (4) and Fast (6). Number 5 indicates the trajectory determined by the expeditions that visited the blast site on the basis of the direction of the fallen trees."

[iamlucky13]

It is unknown what kind of object was involved. You underestimate the amount of energy released when an object breaks apart in the atmosphere at a hypersonic speed. The Tunkuska event could very easily have been the product of a stony meteoroid. Even the "dirty snowball" model of comets has been challenged lately, as it increasingly appears that comets may be more like "snowy dirtballs".

From what I've read lately about comet and meteor research, it's begun to sound to me like there's probably a roughly continuous spectrum of objects from stony asteroid to dirty snowballs. Case-in-point, carbonaceous chondrites are a type of meteorite with a high concentration of water...essentially "snowy dirtballs."

And yes, even dense objects can explode with great force if they break apart. Basically as they disintegrate their surface area to mass ratio skyrockets, and the resulting air drag converts nearly all of their kinetic energy (which can be quite substantial) to heat in a fraction of a second. This doesn't even have to vaporize the meteor material (water, rock, metal, etc), although that does happen, because the air still heats and expands explosively.

The DoD was actually researching the possibility of using this as an area effects weapon. The idea was to accellerate a tungsten rod to hypersonic velocity, then deliberately disintegrate it with a small explosive charge. They're a variation of the "rods from God" bunker buster concept, where instead of bursting it, you using it as a penetrator.

FieryIce, I haven't had a chance to read the links yet, but what was it we missed?

[craterchains]

Read it, it just gives "other" information not covered here so far.

"GB: There is active co-operation between NASA and Russian aerospace officials at a technical, scientific and maybe even military level. Do you liaise or have ties with organisations similar to your own overseas?

VU: I can tell you, truthfully, that just a couple of days before I flew to the United States I had a meeting with my ... let's say, my bosses. And they said they are very interested in co-operating with other organisations ... let's say, our friends in the West. So, I can tell you that this particular mission is at the starting point. I am charged with finding the right people. When this is done, and the next stage is activated, we can make some concrete steps.

GB: Earlier, off camera, you alluded to some important developments concerning the Tunguska explosion of 1908. For the record, can you tell us why you now believe you know the cause?

VU: It is not so much a case of belief; we know what caused it. It was a meteor, but a meteor that was destroyed by ... let's say, a missile. The missile was generated by a material installation. We don't know who constructed it, but it was built long, long ago and is situated in Siberia, several hundred kilometres north of Tunguska. I can tell you that our investigation has revealed more than one explosion at Tunguska. Let me share something with you. The last time that this installation shot down a meteor was on 24/25 September last year. The Americans ... they have three bases ... they, too, noticed this explosion. [Editor's Ref: See New Scientist vol 178 issue 2399 - 14 June 2003]

GB: Forgive me, but some will say this sounds like science fiction.

VU: Graham, you know that when we talk about the truths that lie behind this subject, we only do so with those who have an understanding of the responsibility that goes with it. And you know that we are dealing with a technology much further ahead of our own-one capable of doing things that we cannot."

[FieryIce]

The dazed witnesses reported observing terminators flying above the crash site until the evening of 30 June! These terminator spheres—or "secondary meteors", as they have been interpreted by researchers—were seen by about half of all observers.

I find interesting the use of wording, along with illustrations.


Mysteries of Siberia's "Valley of Death"