Tunguska Explosion Caused by Asteroid Grazing the Earth, Say Scientists
In the early morning of Jun. 30, 1908, a massive explosion flattened entire forests in a remote region of Eastern Siberia along the Tunguska River. Curiously, the explosion left no crater, creating a mystery that has puzzled scientists ever since — what could have caused such a huge blast without leaving any remnants of itself?
Now Daniil Khrennikov at the Siberian Federal University in Russia and colleagues have published a new model of the incident that may finally resolve the mystery. Khrennikov and co say the explosion was caused by an asteroid that grazed the Earth, entering the atmosphere at a shallow angle and then passing out again into space.
“We argue that the Tunguska event was caused by an iron asteroid body, which passed through the Earth’s atmosphere and continued to the near-solar orbit,” they say. If they are correct, the theory suggests Earth escaped an even larger disaster by a hair’s breadth.
First some background. Scientists have long speculated on the cause of the Tunguska impact. Perhaps the most widely discussed idea is that the explosion was the result of an icy body, such as a comet, entering the atmosphere. The ice then rapidly heated up and evaporated explosively in mid-air but without ever hitting the ground.
Little Evidence
Such an explosion could have been powerful enough to flatten trees without leaving a crater. And it would have left little evidence other than vapor in the atmosphere.
But this theory does not fit some of the other evidence. There were just a handful of eyewitness reports of the event. These describe how “the sky split in two,” a huge explosion and widespread fire. But together, they provide evidence that the impactor traveled some 435 miles (700 km) through the atmosphere before the explosion that morning.
So Khrennikov and colleagues simulated the effect of meteorites made of rock, metal or ice, moving through the atmosphere at a speed of 12 miles per second (20 kilometers per second). (Meteorites enter the atmosphere with a minimum speed of 11 kilometers per second.)
Friction with the atmosphere immediately heats these objects. But while iron vaporizes at around 5,432 degrees Fahrenheit (3000 degrees Centigrade), water vaporizes at only 212 degrees F (100 degrees C). So icy meteorites do not last long.
Indeed, Khrennikov and colleagues calculate that an icy body large enough to cause such a large explosion would have traveled no more than 186 miles (300 kilometers) through the atmosphere before vaporizing completely. That suggests the Tunguska meteorite could not have been made of ice.
Instead, Khrennikov and colleagues say a different scenario fits the facts. They say the explosion must have been caused by an iron meteorite about the size of a football stadium. This must have passed through the upper atmosphere, heated rapidly, and then passed out into the Solar System again. The shock wave from this trajectory was what flattened trees.
The shock wave would have caused an explosion of about the right magnitude, and any vaporized iron would have condensed into dust that would be indistinguishable on the ground. Crucially, this scenario would not have left any visible asteroid remnants.
It could also explain reports of dust in the upper atmosphere over Europe after the impact.
Lucky Miss
If Khrennikov and colleagues are correct, then Earth had a lucky near-miss that morning. A direct impact with a 656 foot-wide (200 meter-wide) asteroid would have devastated Siberia, leaving a crater 2 miles (3 kilometers) wide. It would also have had catastrophic effects on the biosphere, perhaps ending modern civilization.
Read more at www.discovermagazine.com
PRINCIPIA SCIENTIFIC INTERNATIONAL, legally registered in the UK as a company 
incorporated for charitable purposes. Head Office: 27 Old Gloucester Street, London WC1N 3AX.
Please DONATE TODAY To Help Our Non-Profit Mission To Defend The Scientific Method.
Trackback from your site.
Jerry Krause
| #
Hi PSI Readers,
An actually observed natural phenomenon.
“Twenty years ago on the Fourth of July, the Boundary Waters Canoe Area Wilderness withstood a storm that transformed the region. The storm, known as a derecho, produced straight-line winds of up to 100 mph, which uprooted and toppled nearly 500,000 acres of the BWCA’s trees in a massive blowdown.”
Have a good day, Jerry
Reply
Jerry Krause
| #
Hi Anyone,
“A derecho (pronounced similar to “deh-REY-cho”) is a widespread, long-lived wind storm that is associated with a band of rapidly moving showers or thunderstorms. … This increases the longevity and strength of the entire system and is what allows the storm to travel such a large area over a short amount of time. (National Weather Service)
A derecho is a widespread, long-lived, straight-line wind storm that is associated with a fast-moving group of severe thunderstorms known as a mesoscale convective system and potentially rivaling hurricanic and tornadic forces. Derechos can cause hurricane-force winds, tornadoes, heavy rains, and flash floods. (Wikipedia)
Hence, this is an observed natural phenomenon that atmospheric scientists generally understand (have explained).
Have a good day, Jerry
Reply
Jerry Krause
| #
And by the way , I was in the direct path of a derecho as an youth during the 1950s. So I have first hand knowledge about them.
Reply
Lloyd.
| #
THAT explains it! You were hit by a Derecho!
Reply
Andy Rowlands
| #
Leonid Kulik took an expedition into Tunguska in the 1930s and mapped the pattern of fallen trees. He also excavated at what he thought was ground zero, but found nothing. From his drawings, and more recent experiments to try and recreate the pattern of fallen trees, it was established the object came in at a shallow angle and disintegrated without actually reaching the ground, hence why no impact crater was found. As an aside, the author Ian Watson wrote a fictionalised account of it called Chekov’s Journey, in which a time-travelling spacecraft malfunctioned and exploded over Tunguska. Rupert Furneaux also wrote a good factual book, gathering all the evidence together, called The Tungus Event.
Reply
Tom O
| #
Asteroids. Climate change. COVID-19. Trump. All subjects of constant fear mongering by the Main Scream Media. I am so tired of “two more asteroids are going to pass by the Earth this week,” NASA says. May I ask, why bring up the subject? A 50 foot rock passing beyond the orbit of the Moon certainly does NOT need to be brought to anyone’s attention, yet they breathlessly report on “the near miss.”
Of course, with the exception of Trump, they can promote “ways for man to protect the Earth” from these science terrors. Trying to figure out what the actual environmental impact on Earth would be if we DID try to find a way to protect Earth from asteroids, leaves my mind spinning. Almost as much as it does to accept “renewables” as a source of power to protect Earth from climate change, or how much change would be needed in the society to protect the snowflakes and friends from undetectable viral infections.
Now, this article in no way is in the category of breathless reporting of “near misses” that I just mentioned. It is nice to see someone trying to solve a “mystery” from the past, as long as it is only the headline writer, and not the authors of the research that stated that this is a fact and not a plausible possibility. I am not sure that I see this explanation as correct as I didn’t think the pattern of fallen trees would support this.
Reply
Jerry Krause
| #
Hi Tom O (not to be confused with TomO),
I want to clarify something so readers do not misinterpret what I have written.
You wrote: “I am not sure that I see this explanation as correct as I didn’t think the pattern of fallen trees would support this.”
First if I happen to write ‘ I think” it means I am clueless.and what I think is nonsense. Second, just because I offer an observed explanation for a large area of fallen trees does not mean the asteroid explanation in this other case is wrong. It is that good science requires one to do a literature search to see if there might be an alternative explanation of what is clearly seen. Or to make an effort to examine this event as mentioned by Andy as having been done. Which result doesn’t prove anything as the there could be no particles of the asteroid if it was a near miss as proposed.
Why does one need to do an exhaustive literature search before being any research project? To avoid doing an year of more doing the research, only to discover that it had been done before and therefore your efforts do not qualify as being original and one need to start again after learning this critically important lesson. Fortunately I discovered that the research project suggested by my major professor had been done before I had invested too much time and effort.
But in this case, one cause of downed trees is absolutely known and the other is merely a reasoned theory.
Wrong ideas that become accept6ed ideas greatly hinder progress as documented by the several wrong ideas of Aristotle and his philosopher buddies which were accepted for a couple thousands of years.
Have a good day, Jerry
Have a good day, Jerry..
You wrote: “
Reply
Allan Shelton
| #
Look at the source……..
Read more at http://www.discovermagazine.com
They are well known for pseudo-science
Reply