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Gloster Meteor F Mk.6

Gloster Meteor F Mk.6

Gloster Meteor F Mk.6

The Gloster Meteor F.Mk.6 was a proposal for an improved version of the Meteor jet, made early in 1946. It would have features Rolls Royce Derwent 7 engines carried in long engine nacelles, with the Mk.4 short span wings and the high tail designed for the Gloster E.1/44 single engined fighter. Work on the Mk.6 was abandoned in favour of the Mk.8, the final and best day fighter version of the Meteor.

Gloster Meteor F Mk.6 - History

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      MK Martin's Meteor series 3PH snowblowers are built to get your work off the ground with durable performance and high-capacity design. The Meteor is available in a range of models for 12 HP compact tractors to 175 HP farm tractors.

      Models SB48 SB54 SB60 SB68 SB72 SB78 SB87 SB97
      HP (Rec.) 12 HP 15 HP 20 HP 30 HP 35 HP 50 HP 60 HP 75 HP
      Cutting Width 48" 54" 60" 68" 72" 78" 87" 97"
      Cutting Edge 1/4 x 1-1/2 3/8 x 1 3/8 x 1 3/8 x 1 3/8 x 1 1/2 x 1-1/2 1/2 x 2 1/2 x 2
      Auger Diam. 12" 14" 14" 14" 14" 15" 19" 19"
      Fan Diam. 19" 21" 21" 21" 21" 23" 27" 27"
      Chute Diam. 7" 8" 8" 10" 10" 10" 12" 12"
      Chute Rotation Manual Included Select Option
      Chute Deflector Manual Manual Standard/ Hydraulic Option Manual Standard/ Hydraulic Option
      Main Body Height 22.5" 25" 25" 29" 29" 29" 36" 36"
      3PH Mount CAT. 1 CAT. 1 CAT. 1 CAT. 1 CAT. 1 CAT. 1 & 2 CAT. 2 CAT. 2
      Weight (LBS.) 266 366 396 506 540 748 1,034 1,106

      3PH / Quick Attach

      All single auger PTO driven models are built for Category 1 or Category 2 type 3PH. Dual auger PTO driven models are built for Category 2 or Category 3 type 3PH. All models are Quick Attach compatible.

      High Tensile Steel Ribbon Flighting

      To deliver even the heaviest wet snow to the awaiting fan, Meteor Snow Blowers use machine formed hand welded augers made with high tensile steel ribbon flighting to provide strength and durability for years to come.

      Five Blade Fan

      All Meteor Snow Blowers now feature a standard 5 blade fan. The five blades not only evacuate high volumes of snow quickly, but also feature tighter tolerance to the housing increasing velocity of the snow exiting the chute.

      Gear Box

      The time-proven Comer gearbox transfers PTO power from the tractor into the driveline of the Meteor. Ensuring consistent power input to the auger and fan assemblies.

      Manual Deflector

      All Meteor Snow Blowers come with a manual pin style deflector allowing a true set it and forget approach to blowing snow.

      Skid Shoes

      Meteor Snow Blowers come equipped with adjustable skid shoes extending the life of the cutting edge and helping to protect surfaces from damage commonly associated with snow removal.

      Manual Rotator

      Manual rotators are standard on SB48, SB54, and SB60 single auger models and can be optionally outfitted on most models where operators can safely reach the adjustment handle.

      Hydraulic Rotator

      The optional hydraulic rotator is the ideal upgrade for tractors with cabs or for contractors/property managers needing to make frequent adjustments.

      Hydraulic rotators are standard equipment on SB97D, SB108D, and SB120D models.

      Electric Rotator

      When hydraulic power isn't available the 12V electric rotator provides a hands off approach to chute rotation.

      Contact MK Martin for compatibility and availability.

      Hydraulic Deflector

      Hydraulic deflectors control the distance and arc of the thrown snow and are an available option on all models.

      Multi-Hinged Deflector

      The optional multi-hinged deflector is available for most models and allows increased precision in where snow is blown allowing snow to be placed closer to the blower or into a truck to be hauled away.


      During the Battle of the Netherlands, many Dutch planes were destroyed by Nazi Germany's forces, but 350 German planes were shot down by the Dutch forces. After the battle, many pilots fled to the United Kingdom to continue the fight as part of the Allies. Then, on 12 June 1943, a separate squadron within the Royal Air Force was formed with Dutch pilots already flying in the RAF. That was the first official beginning of the No. 322 squadron. From then 322 Squadron also actively participated in the war and fought along the allied forces until the end of the war.

      After the war, it was disbanded as a RAF squadron and formed part of the Dutch armed forces. There was no certain future for the squadron. It was deactivated and reactivated several times. It did serve in the Dutch East Indies and Netherlands New Guinea. The squadron was stationed at both Twente Air Base and Soesterberg Air Base. In 1964, the squadron was finally stationed at a permanent base, Leeuwarden Air Base, where it was permanently assigned with the air defense task. Probably the most unusual mission in the squadron's history was performed on Saturday morning 11 June 1977 at 05:00 AM. With thundering afterburners, six of its fighter jets flew several very low passes over a hijacked train, initiating a successful operation that ended the 1977 Dutch train hostage crisis. Since the 1990s the squadron took part in several NATO and UN missions. During the Yugoslav Wars 322 Squadron made several deployments to Villafranca Air Base near Verona. From there it flew NATO missions over the former Yugoslavia. In 1995, during the fall of Srebrenica, two of its F-16s delivered the only bombs on the advancing Bosnian-Serb troops. The occasion marked the first attack by a female combat pilot in NATO, who scored a direct hit on a rolling Serbian tank using an (unguided) Mark 82 bomb. Since 2003, the squadron has seen action over Afghanistan.

      Together with Volkel Air Base, the 322 Squadron is on constant duty, ready for Quick Reaction Alert. Since 1964 when equipped with the F-104G Starfighter until today, the squadron is constantly practicing its tasks. Nowadays, the squadron has a swing-role task. These include air defense and ground support tasks, and the F-16 fighters can be reconfigured to handle new tasks anytime by changing their weapons loads. The squadron is constantly active and ready for deployment to crisis situations like Libya and Afghanistan. Because of financial cuts to the Ministry of Defense, the number of possessed F-16s has decreased to around 60 F-16 multi-role fighter jets. There are four squadrons with around 15 F-16s per squadron, including No. 322 Squadron. The main tasks are air defense and ground support roles, but other tasks are to:

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      Operation Midnight Climax

      Operation Midnight Climax was an MK-Ultra project in which government-employed prostitutes lured unsuspecting men to CIA “safe houses” where drug experiments took place.

      The CIA dosed the men with LSD and then—while at times drinking cocktails behind a two-way mirror—watched the drug’s effects on the men’s behavior. Recording devices were installed in the prostitutes’ rooms, disguised as electrical outlets.

      Most of the Operation Midnight Climax experiments took place in San Francisco and Marin County, California, and in New York City. The program had little oversight and the CIA agents involved admitted that a freewheeling, party-like atmosphere prevailed.

      An agent named George White wrote to Gottlieb in 1971: “Of course I was a very minor missionary, actually a heretic, but I toiled wholeheartedly in the vineyards because it was fun, fun, fun. Where else could a red-blooded American boy lie, kill and cheat, steal, deceive, rape and pillage with the sanction and blessing of the All-Highest?”

      Gloster Meteor F Mk.6 - History

      Hawker Hunter Prototype WB188

      Hawker Hunter Development Aircraft P.1081

      Hawker Hunter prototype (WB188) - The record breaking Hunter

      Hawker Hunter (WB188) taxying for take off with Neville Duke at the controls

      After the Iran-Iraq War of the 1980s, Iraq was in debt to Kuwait and the United Arab Emirates, who had financed its war efforts. Iraqi President Saddam Hussein insisted both countries cancel that debt because he felt they owed him for protecting them against Iran. Both countries refused, however, so Hussein threatened Kuwait, its oil-rich, militarily-weak neighbor, reigniting a decades-old border dispute over Kuwait itself.

      In July 1990, Saddam claimed that Kuwait and the UAE were over producing crude oil, driving down prices and depriving Iraq of critical oil revenues. He accused Kuwait of stealing from an oil field on the Iraq-Kuwait border, and he accused the U.S. and Israel of encouraging Kuwait to lower its oil prices.

      Relations deteriorated with all parties, which led to Hussein invading and annexing Kuwait in August 1990.The United Nations Security Council placed an embargo and sanctions on Iraq, but months later, when Hussein refused to comply with a resolution requiring him to withdraw, Desert Storm began.

      August 12 — Perseid Meteor Shower

      A Perseid meteor streaks through the sky above the European Southern Observatory's Very Large Telescope. (ESO / Stéphane Guisard)

      The Perseids is one of the most popular meteor showers of the year, peaking in the warm summer nights of August. This year, shooting stars should be visible in the nights and early mornings of August 11, 12 and 13, with the shower’s peak occurring in the predawn hours of August 12. Meteors will be visible across the sky, and if you trace their path, they appear to be radiating from the constellation Perseus.

      At its peak, the shower could produce about a meteor every minute, although the last quarter moon will drown out some of the meteors with its light. For best viewing conditions, find a spot outdoors away from any major cities, and remember that it takes about 20 minutes for your eyes to fully adjust to the darkness.

      When is the next meteor shower?


      Status: Active from April 16th to April 30th

      Peak: Apr 21-22 2021 (Moon 68% full.)

      Eta Aquariids

      Status: Active from April 19th to May 28th

      Peak: May 4-5 2021 (Moon 38% full.)


      The Lyrids are a medium strength shower that usually produces good rates for three nights centered on the maximum. These meteors also usually lack persistent trains but can produce fireballs. These meteors are best seen from the northern hemisphere where the radiant is high in the sky at dawn. Activity from this shower can be seen from the southern hemisphere, but at a lower rate.

      Shower details - Radiant: 18:04 +34° - ZHR: 18 - Velocity: 30 miles/sec (medium - 48.4km/sec) - Parent Object: C/1861 G1 (Thatcher)

      Next Peak - The Lyrids will next peak on the Apr 21-22, 2021 night. On this night, the moon will be 68% full.

      Eta Aquariids

      The Eta Aquariids are a strong shower when viewed from the southern tropics. From the equator northward, they usually only produce medium rates of 10-30 per hour just before dawn. Activity is good for a week centered the night of maximum activity. These are swift meteors that produce a high percentage of persistent trains, but few fireballs.

      Shower details - Radiant: 22:32 -1° - ZHR: 40 - Velocity: 42 miles/sec (swift - 66.9km/sec) - Parent Object: 1P/Halley

      Next Peak - The eta Aquariids will next peak on the May 4-5, 2021 night. On this night, the moon will be 38% full.

      Southern delta Aquariids

      The Delta Aquariids are another strong shower best seen from the southern tropics. North of the equator the radiant is located lower in the southern sky and therefore rates are less than seen from further south. These meteors produce good rates for a week centered on the night of maximum. These are usually faint meteors that lack both persistent trains and fireballs.

      Shower details - Radiant: 22:40 -16.4° - ZHR: 16 - Velocity: 26 miles/sec (medium - 41km/sec) - Parent Object: 96P/Machholz?

      Next Peak - The Southern delta Aquariids will next peak on the Jul 28-29, 2021 night. On this night, the moon will be 74% full.

      Alpha Capricornids

      The Alpha Capricornids are active from July 3 through August 15 with a "plateau-like" maximum centered on July 30. This shower is not very strong and rarely produces in excess of five shower members per hour. What is notable about this shower is the number of bright fireballs produced during its activity period. This shower is seen equally well on either side of the equator.

      Shower details - Radiant: 20:28 -10.2° - ZHR: 5 - Velocity: 15 miles/sec (slow - 24km/sec) - Parent Object: 169P/NEAT

      Next Peak - The alpha Capricornids will next peak on the Jul 28-29, 2021 night. On this night, the moon will be 74% full.


      The Perseids are the most popular meteor shower as they peak on warm August nights as seen from the northern hemisphere. The Perseids are active from July 17 to August 24. They reach a strong maximum on August 12 or 13, depending on the year. Normal rates seen from rural locations range from 50-75 shower members per hour at maximum.The Perseids are particles released from comet 109P/Swift-Tuttle during its numerous returns to the inner solar system. They are called Perseids since the radiant (the area of the sky where the meteors seem to originate) is located near the prominent constellation of Perseus the hero when at maximum activity.

      Shower details - Radiant: 03:12 +57.6° - ZHR: 100 - Velocity: 37 miles/sec (swift - 60km/sec) - Parent Object: 109P/Swift-Tuttle

      Next Peak - The Perseids will next peak on the Aug 11-12, 2021 night. On this night, the moon will be 13% full.


      The Orionids are a medium strength shower that sometimes reaches high strength activity. In a normal year the Orionids produce 10-20 shower members at maximum. In exceptional years, such as 2006-2009, the peak rates were on par with the Perseids (50-75 per hour). Recent displays have produced low to average displays of this shower.

      Shower details - Radiant: 06:20 +15.5° - ZHR: 20 - Velocity: 41 miles/sec (swift - 67km/sec) - Parent Object: 1P/Halley

      Next Peak - The Orionids will next peak on the Oct 20-21, 2021 night. On this night, the moon will be 100% full.

      Southern Taurids

      The Southern Taurids are a long-lasting shower that several minor peaks during its activity period. The shower is active for more than two months but rarely produces more than five shower members per hour, even at maximum activity. The Taurids (both branches) are rich in fireballs and are often responsible for increased number of fireball reports from September through November.

      Shower details - Radiant: 03:12 +12.8° - ZHR: 5 - Velocity: 16.5 miles/sec (slow - 26.6km/sec) - Parent Object: 2P/Encke

      Next Peak - The Southern Taurids will next peak on the Nov 2-3, 2021 night. On this night, the moon will be 5% full.

      Northern Taurids

      This shower is much like the Southern Taurids, just active a bit later in the year. When the two showers are active simultaneously in late October and early November, there is sometimes an notable increase in the fireball activity. There seems to be a seven year periodicity with these fireballs. 2008 and 2015 both produced remarkable fireball activity.

      Shower details - Radiant: 03:52 +22.7° - ZHR: 5 - Velocity: 18 miles/sec (medium - 30km/sec) - Parent Object: 2P/Encke

      Next Peak - The Northern Taurids will next peak on the Nov 11-12, 2021 night. On this night, the moon will be 55% full.


      The Leonids are best known for producing meteor storms in the years of 1833, 1866, 1966, 1999, and 2001. These outbursts of meteor activity are best seen when the parent object, comet 55P/Tempel-Tuttle, is near perihelion (closest approach to the sun). Yet it is not the fresh material we see from the comet, but rather debris from earlier returns that also happen to be most dense at the same time. Unfortunately it appears that the earth will not encounter any dense clouds of debris until 2099. Therefore when the comet returns in 2031 and 2064, there will be no meteor storms, but perhaps several good displays of Leonid activity when rates are in excess of 100 per hour. The best we can hope for now until the year 2030 is peaks of around 15 shower members per hour and perhaps an occasional weak outburst when the earth passes near a debris trail. The Leonids are often bright meteors with a high percentage of persistent trains.

      Shower details - Radiant: 10:08 +21.6° - ZHR: 15 - Velocity: 44 miles/sec (swift - 71km/sec) - Parent Object: 55P/Tempel-Tuttle

      Next Peak - The Leonids will next peak on the Nov 16-17, 2021 night. On this night, the moon will be 95% full.


      The Geminids are usually the strongest meteor shower of the year and meteor enthusiasts are certain to circle December 13 and 14 on their calendars. This is the one major shower that provides good activity prior to midnight as the constellation of Gemini is well placed from 22:00 onward. The Geminids are often bright and intensely colored. Due to their medium-slow velocity, persistent trains are not usually seen. These meteors are also seen in the southern hemisphere, but only during the middle of the night and at a reduced rate.

      Shower details - Radiant: 07:28 +32.2° - ZHR: 150 - Velocity: 22 miles/sec (medium - 35km/sec) - Parent Object: 3200 Phaethon (asteroid)

      Next Peak - The Geminids will next peak on the Dec 13-14, 2021 night. On this night, the moon will be 78% full.


      The Ursids are often neglected due to the fact it peaks just before Christmas and the rates are much less than the Geminds, which peaks just a week before the Ursids. Observers will normally see 5-10 Ursids per hour during the late morning hours on the date of maximum activity. There have been occasional outbursts when rates have exceeded 25 per hour. These outbursts appear unrelated to the perihelion dates of comet 8P/Tuttle. This shower is strictly a northern hemisphere event as the radiant fails to clear the horizon or does so simultaneously with the start of morning twilight as seen from the southern tropics.

      Shower details - Radiant: 14:28 +74.8° - ZHR: 10 - Velocity: 20 miles/sec (medium - 32km/sec) - Parent Object: 8P/Tuttle

      Next Peak - The Ursids will next peak on the Dec 21-22, 2021 night. On this night, the moon will be 93% full.


      The Quadrantids have the potential to be the strongest shower of the year but usually fall short due to the short length of maximum activity (6 hours) and the poor weather experienced during early January. The average hourly rates one can expect under dark skies is 25. These meteors usually lack persistent trains but often produce bright fireballs. Due to the high northerly declination (celestial latitude) these meteors are not well seen from the southern hemisphere.

      Shower details - Radiant: 15:18 +49.5° - ZHR: 120 - Velocity: 26 miles/sec (medium - 42.2km/sec) - Parent Object: 2003 EH (Asteroid)

      Next Peak - The Quadrantids will next peak on the Jan 2-3, 2022 night. On this night, the moon will be 0% full.

      In Siberia in 1908, a huge explosion came out of nowhere

      On 30 June 1908, an explosion ripped through the air above a remote forest in Siberia, near the Podkamennaya Tunguska river.

      The fireball is believed to have been 50-100m wide. It depleted 2,000 sq km of the taiga forest in the area, flattening about 80 million trees.

      The earth trembled. Windows smashed in the nearest town over 35 miles (60km) away. Residents there even felt heat from the blast, and some were blown off their feet.

      The crash was followed by a noise like stones falling from the sky, or of guns firing

      Fortunately, the area in which this massive explosion occurred was sparsely inhabited. There were no official reports of human casualties, though one local deer herder reportedly died after he was thrust into a tree from the blast. Hundreds of reindeer were also reduced to charred carcasses.

      One eyewitness account said that "the sky was split in two, and high above the forest the whole northern part of the sky appeared covered with fire&hellip

      "At that moment there was a bang in the sky and a mighty crash&hellip The crash was followed by a noise like stones falling from the sky, or of guns firing."

      This "Tunguska event" remains the most powerful of its kind recorded in history &ndash it produced about 185 times more energy than the Hiroshima atomic bomb (with some estimates coming in even higher). Seismic rumbles were even observed as far away as the UK.

      And yet, over a hundred years later researchers are still asking questions about what exactly took place on that fateful day. Many are convinced that it was an asteroid or a comet that was responsible for the blast. But very few traces of this large extraterrestrial object have ever been found, opening the way for more outlandish explanations for the explosion.

      The Tunguska region of Siberia is a remote place, with a dramatic climate. It has a long hostile winter and a very short summer, when the ground changes into a muddy uninhabitable swamp. This makes the area extremely hard to get to.

      When the explosion happened, nobody ventured to the site to investigate. This was partly because the Russian authorities had more pressing concerns than sating scientific curiosity, says Natalia Artemieva of the Planetary Science Institute in Tucson, Arizona.

      He found a large area of flattened trees, spreading out about 50km wide

      Political strife in the country was growing &ndash World War One and the Russian Revolution were just a few years away. "There were only some publications in local papers, not even in St Petersburg or Moscow," she says.

      It was only a few decades later, in 1927, that a Russian team led by Leonid Kulik finally made a trip to the area. He had stumbled across a description of the event six years earlier and convinced Russian authorities that a trip would be worthwhile. When he got there, the damage was still immediately apparent, almost 20 years after the blast.

      He found a large area of flattened trees, spreading out about 31 miles (50km) wide in a strange butterfly shape. He proposed that an extraterrestrial meteor had exploded in the atmosphere.

      It puzzled him that there was no impact crater, or in fact, any meteoric remnants at all. To explain this, he suggested that the swampy ground was too soft to preserve whatever hit it and that any debris from the collision had been buried.

      Kulik still hoped that he could uncover the remains, as he wrote in his 1938 conclusions. "We should expect to encounter, at a depth of hardly less than 25 metres, crushed masses of this nickeliferous iron, individual pieces of which may have a weight of one or two hundred metric tons."

      Some suggested the Tunguska event could have been the result of matter and antimatter colliding

      Russian researchers later said that it was a comet, not a meteor that caused the damage. Comets are largely made up of ice &ndash not rock, like meteorites &ndash so the absence of alien rock fragments would make more sense this way. The ice would have started to evaporate as it entered Earth's atmosphere, and continue to do so as it hit the ground.

      But that was not the end of the debate. Because the exact identity of the explosion was unclear, strange alternative theories soon started to appear.

      Some suggested the Tunguska event could have been the result of matter and antimatter colliding. When this happens, the particles annihilate and emit intense bursts of energy.

      Another proposal was that a nuclear explosion caused the blast. An even more outlandish suggestion was that an alien spaceship crashed at the site on its search for the fresh water of Lake Baikal.

      As you might expect, none of these theories stuck. Then, in a 1958 expedition to the site, researchers discovered tiny remnants of silicate and magnetite in the soil.

      Further analysis showed they were high in nickel, a known characteristic of meteoric rock. The meteor explanation looked correct after all &ndash and K. Florensky, author of a 1963 report on the event, was keen to put the more fantastical theories to rest:

      They were more concerned with bigger asteroids that might cause global extinctions

      "While I am aware of the advantages of sensational publicity in drawing public attention to a problem, it should be stressed that unhealthy interest aroused as a result of distorted facts and misinformation should never be used as a basis for the furtherance of scientific knowledge."

      But that did not stop others coming up with even more imaginative ideas. In 1973 a paper was published in the reputable journal Nature, suggesting that a black hole collided into Earth to cause the explosion. This was quickly disputed by others.

      Artemieva says ideas like this are simply a by-product of human psychology. "People who like secrets and 'theories' usually do not listen to scientists," she says. A huge explosion, coupled with a lack of cosmic remnants, is ripe for these kinds of speculations.

      But she also says scientists must shoulder some responsibility, because they took so long to analyse the explosion site. They were more concerned with bigger asteroids that might cause global extinctions, just as the Chicxulub asteroid did. It wiped out most of the dinosaurs 66 million years ago.

      In 2013 one team put a stop to much of the speculation of the earlier decades. Led by Victor Kvasnytsya of the National Academy of Sciences of Ukraine, the researchers analysed microscopic samples of rocks collected from the explosion site in 1978. The rocks had a meteoric origin. Crucially, the fragments they analysed were recovered from a layer of peat dating back to 1908.

      Various gravitational interactions can make [asteroids] change their orbit more dramatically

      The remnants had traces of a carbon mineral called lonsdaleite, which has a crystal structure almost like diamond. This particular mineral is known to form when a graphite-containing structure, such as a meteor, crashes into Earth.

      "Our study of samples from Tunguska, as well as research of many other authors reveals meteorite origin of Tunguska event," says Kvasnytsya. "We believe that nothing paranormal happened at Tunguska."

      The main problem, he says, is that researchers had spent too much time looking for large pieces of rock. "What was necessary was to look for very small particles," such as the ones his team studied.

      But it is not a definitive conclusion. Meteor showers occur often. Many small ones might therefore sprinkle their remnants onto Earth unnoticed. Samples with meteoric origin could presumably come from one of these. Some researchers also cast doubt that the peat collected dates from 1908.

      Even Artemieva says she needs to revise her models to understand the total absence of meteorites at Tunguska.

      Still, in line with Leonid Kulik's early observations, today the broad consensus remains that the Tunguska event was caused by a large cosmic body, like an asteroid or comet, colliding with Earth's atmosphere.

      Most asteroids have quite stable orbits, many of which are found in the asteroid belt between Mars and Jupiter. However, "various gravitational interactions can make them change their orbit more dramatically," says Gareth Collins of Imperial College London, UK.

      Occasionally these rocky bodies can cross over into Earth's orbit which can put them onto a collision course with us. At the point one enters into our atmosphere and begins to fragment, it is known as a meteor.

      What made the Tunguska event so dramatic was that it was an extremely rare case of what researchers call a "megaton" event &ndash as the energy emitted was about 10-15 megatons of TNT, though even higher estimates have also been proposed.

      This is also why the Tunguska event has been difficult to make full sense of. It is the only event of that magnitude that has happened in recent history. "That limits our understanding," says Collins.

      Artemieva now says there are clear stages that took place, which she has outlined in a review to be published in the Annual Review of Earth and Planetary Sciences in the second half of 2016.

      Most people think they come whaling in from outer space and leave a crater

      First, the cosmic body entered our atmosphere at 9-19 miles per second (15-30km/s).

      Fortunately, our atmosphere is good at protecting us. "It will break apart a rock smaller than a football field across," explains NASA researcher Bill Cooke, who leads NASA's Meteoroid Environment Office. "Most people think they come whaling in from outer space and leave a crater, and there's a big smoking piece of rock on the ground. The truth is kind of the opposite."

      The atmosphere will generally break rocks up a few kilometres above the Earth's surface, producing an occasional shower of smaller rocks that, by the time they hit the ground, will be cold.

      In the case of Tunguska, the incoming meteor must have been extremely fragile, or the explosion so intense, it obliterated all its remnants 8-10km above Earth.

      This process explains the event's second stage. The atmosphere vaporised the object into tiny pieces, while at the same time intense kinetic energy also transformed them into heat.

      "The process is similar to a chemical explosion. In conventional explosions, chemical or nuclear energy is transformed into heat," says Artemieva.

      The intense heat resulted in shockwaves that were felt for hundreds of kilometres

      In other words, any remnants from whatever entered Earth's atmosphere were turned into cosmic dust in the process.

      If events unfolded this way, it explains the lack of large chunks of cosmic material at the site. "It is very difficult to find a millimetre-size grain in a big area. It is necessary to search in the peat," says Kvasnytsya.

      As the object entered our atmosphere and broke apart, the intense heat resulted in shockwaves that were felt for hundreds of kilometres. When this airburst then hit the ground it flattened all the trees in the vicinity.

      Artemieva suggests an enormous plume resulted from the updraught, which was then followed by a cloud, "thousands of kilometres in diameter".

      But Tunguska's story is not over. Even now, some other researchers have proposed that we have been missing an obvious clue to explain the event.

      In 2007 an Italian team suggested that a lake 5 miles (8km) north-north-west of the explosion's epicentre could be an impact crater. Lake Cheko, they say, did not feature on any maps before the event.

      Luca Gasperini of the University of Bologna in Italy, travelled to the lake in the late 1990s, and says it is difficult to explain the origin of the lake in any other way. "Now we are sure it was formed after the impact, not from the main Tunguska body but of a fragment of the asteroid that was preserved by the explosion."

      Any 'enigmatic' objects at the bottom of this lake could be easily recovered with minimal efforts

      Gasperini firmly believes that a large piece of asteroid lies 33ft (10m) below the bottom of the lake, buried in sediment. "It would be very easy for Russians to get there and drill," he says. Despite heavy criticism of the theory, he still hopes someone will scour the lake for remnants of meteoric origin.

      That Lake Cheko is an impact crater is not a popular idea. It is just another "quasi-theory" says Artemieva. "Any 'enigmatic' objects at the bottom of this lake could be easily recovered with minimal efforts &ndash the lake is not deep," she says. Collins also disagrees with Gasperini's idea.

      In 2008, he and colleagues published a rebuttal to the theory, stating that "unaffected mature trees" were close to the lake, which would have been obliterated if a large piece of rock had fallen close by.

      Regardless of the details, the influence of the Tunguska event is still felt. Research papers on the subject continue to be published.

      Today, astronomers also peer into the skies with powerful telescopes to look for signs that rocks with the potential to cause a similar event are heading our way, and to assess the risk that they pose.

      When a Tunguska type event happens again, the overwhelming probability is that it will happen nowhere near human population

      In 2013 in Chelyabinsk, Russia, a relatively small meteor around 62ft (19m) wide created visible disruption. This surprised researchers like Collins. His models had predicted it would not cause as much damage as it did.

      "What's challenging is that this process of the asteroid disrupting in the atmosphere, decelerating, evaporating and transferring its energy to the air, is a very complicated process. We would like to understand it more, to better predict consequences of these events in future."

      Chelyabinsk-sized meteors were previously believed to occur roughly every 100 years, while Tunguska-sized events had been predicted to occur once a millennium. This figure has since been revised. Chelyabinsk-sized meteors could be happening 10 times more frequently, says Collins, while Tunguska style impacts could occur as often as once every 100-200 years.

      Unfortunately, we are and will remain defenceless against similar events, says Kvasnytsya. If another explosion like the Tunguska event took place above a populated city, it would cause thousands if not millions of casualties, depending where it hit.

      But it is not all bad news. The probability of that happening is extremely small, says Collins, especially given the huge surface area of Earth that is covered in water. "When a Tunguska-type event happens again, the overwhelming probability is that it will happen nowhere near human population."

      We may never find out whether the Tunguska event was caused by a meteor or comet, but in a way that does not matter. Either could have resulted in the intense cosmic disruption, which we are still talking about over a century later.

      Melissa Hogenboom is BBC Earth's feature writer. She is @melissasuzanneh on Twitter.

      Watch the video: Gloster Meteor - A Short History (January 2022).