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Eksplozja meteoru nad Morzem Beringa (18.12.2018)
« dnia: Marzec 20, 2019, 07:40 »
Słabszy o 40% od Czelabińska wybuch  meteoru    miał miejsce 18 grudnia 2018 i był drugim pod względem energetycznym w ciągu ostatnich 30 lat.

Meteor blast over Bering Sea was 10 times size of Hiroshima
Mon 18 Mar 2019 12.19 GMT Last modified on Mon 18 Mar 2019 20.50 GMT

Fireball over Kamchatka peninsula in December went largely unnoticed at the time

A meteor explosion over the Bering Sea late last year unleashed 10 times as much energy as the atomic bomb that destroyed Hiroshima, scientists have revealed.

The fireball tore across the sky off Russia’s Kamchatka peninsula on 18 December and released energy equivalent to 173 kilotons of TNT. It was the largest air blast since another meteor hurtled into the atmosphere over Chelyabinsk, in Russia’s south-west, six years ago, and the second largest in the past 30 years.

Unlike the Chelyabinsk meteor, which was captured on CCTV, mobile phones and car dashboard cameras, the December arrival from outer space went largely unnoticed at the time because it exploded in such a remote location.

Nasa received information about the blast from the US air force after military satellites detected visible and infrared light from the fireball in December. Lindley Johnson, a planetary defence officer at Nasa,

The space agency’s analysis shows that the meteor, probably a few metres wide, barrelled into Earth’s atmosphere at 72,000mph and exploded at an altitude of 16 miles. The blast released about 40% of the energy of the meteor explosion over Chelyabinsk, according to Kelly Fast, Nasa’s near-Earth objects observations programme manager, who spoke at the 50th Lunar and Planetary Science conference near Houston.

Since the event came to light, meteor researchers have been asking airlines for any sightings of the fireball, which came in close to routes used by commercial carriers flying between North America and Asia.

Peter Brown, a meteor specialist at Western University in Canada, spotted the blast independently in measurements made by global monitoring stations. The explosion left its mark in data recorded by a network of sensors that detect infrasound, which has a frequency too low for the human ear to pick up. The network was set up to detect covert nuclear bomb tests.

The Bering Sea event is another reminder that despite efforts to identify and track space rocks that could pose a threat to Earth, sizeable meteors can still arrive without warning. Nasa is working to identify 90% of near-Earth asteroids larger than 140 metres by 2020, but the task could take another 30 years to complete.

The 20m-wide meteor that detonated over Chelyabinsk lit up the morning sky on 15 February 2013. At its most intense, the fireball burned 30 times brighter than the sun. The flash quickly gave way to a shockwave that knocked people off their feet and shattered windows in thousands of apartments. No one was killed but more than 1,200 people were injured, many by flying glass. Some sustained retinal burns from watching the spectacle. (...)

https://www.theguardian.com/science/2019/mar/18/meteor-blast-over-bering-sea-was-10-times-size-of-hiroshima
https://edition.cnn.com/2019/03/18/us/meteor-blast-fireball-explosion-nasa-space-trnd/index.html
https://www.iflscience.com/space/a-meteor-exploded-over-earth-with-the-force-of-10-atomic-bombs-and-we-all-totally-missed-it/
« Ostatnia zmiana: Marzec 20, 2019, 07:55 wysłana przez Orionid »

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Odp: Eksplozja meteoru nad Morzem Beringa (18.12.2018)
« Odpowiedź #1 dnia: Marzec 20, 2019, 07:46 »
The powerful meteor that no one saw (except satellites)
March 19, 2019 by Ivan Couronne With Pascale Mollard In Paris


A meteor streaking through the night sky over Myanmar during the Geminid meteor shower on December 14 2018.

At precisely 11:48 am on December 18, 2018, a large space rock heading straight for Earth at a speed of 19 miles per second exploded into a vast ball of fire as it entered the atmosphere, 15.9 miles above the Bering Sea.

From below, the only witnesses to this fiery event may have been the fish that inhabit the frigid waters between Russia and Alaska, as no human eye caught sight of it.

A meteor is the luminous phenomenon that results when an asteroid or other celestial body enters the Earth's atmosphere. It is commonly called a shooting star. If it does not fully vaporize and some part of it hits the Earth's surface, it is called a meteorite.

One of the first researchers to detect the event was Peter Brown, a meteor scientist at the Department of Physics and Astronomy at the University of Western Ontario.

On March 8, he was poring over December data from the system used by the Comprehensive Test Ban Treaty Organization to detect atmospheric explosions caused by nuclear tests.

The system is comprised of seismic and acoustic sensors capable of picking up infrasound, inaudible to the human ear, at a distance of tens of thousands of miles.

"Many of them detected the sound waves from this explosion," he told AFP. "If you were directly under it, it would have been deafening."

10 meters in diameter

US military satellites spotted the explosion immediately.

But it was not until March 8 that the Air Force officially informed NASA, which logged the event in the database of fireballs it has kept since 1988, according to Lindley Johnson, NASA's Planetary Defense Officer.

"It was almost immediately published on our website, within 10 minutes, I would say," he told AFP.

NASA's Center for Near Earth Object Studies calculated the energy released by the explosion to be 173 kilotons, more than 10 times as destructive as the 15-kiloton atomic bomb that leveled Hiroshima in 1945.

It was the most powerful explosion in the atmosphere since the fireball that burst over the Russian town of Chelyabinsk in 2013. That was 440 kilotons, and left 1,500 people injured, mostly from glass flying out of smashed windows.

The event was described on Monday by scientists at the 50th Lunar and Planetary Science Conference in Texas.

When he read a report on the subject on the BBC, Simon Proud, a meteorologist and specialist in satellite data at Oxford University, decided to check the archive of images collected by a Japanese weather satellite, Himawari, which his center permanently monitors.

Bingo: the satellite was in the right place at the right time, he told AFP.

Proud published the image on his Twitter account: what looks like an orange ball of fire above the clouds and sea, but which is in fact a cloud of dust from the meteor caught in the sunlight, Brown said.

As it turns out, NASA's MODIS satellite also photographed the dust cloud, the agency's Kurtis Thome told AFP Tuesday.

"It doesn't surprise me," said Patrick Michel, research director and asteroid specialist at the observatory of the Cote d'Azur in southern France.

"It is a good reminder that there are a bunch of these things that pass over our heads and that it would be good to be more concerned about them," he told AFP.

"It should remind us that even if it is the least likely natural risk we face, it is a still a risk that exists and will in the long term become a reality," he said.

The rock was roughly 10 meters (33 feet) in diameter: the most dangerous celestial bodies for the Earth are those in excess of 150 meters.

"Nothing very unusual," said Rudiger Jehn, head of planetary defense at the European Space Agency (ESA).

"We were lucky it was over the ocean. It can happen again, and someday there will be a bigger one," he said, noting that the ESA plans to ask member states for a budget to create a better protection system against asteroids during a ministerial meeting in November.

"That meteor explosion is a perfect promotion for our program. And it is free," he said.

© 2019 AFP
https://phys.org/news/2019-03-powerful-meteor-satellites.html#jCp
« Ostatnia zmiana: Marzec 20, 2019, 07:55 wysłana przez Orionid »

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Odp: Eksplozja meteoru nad Morzem Beringa (18.12.2018)
« Odpowiedź #2 dnia: Marzec 20, 2019, 08:24 »
Simon Proud@simon_sat 19 mar 2019

A video showing the smoke trail from the #Meteor over the Bering Strait last December, produced using data from @JMA_kishou's #Himawari satellite.
The orange meteor trail in the middle, shadow above-left.
Hi-res copy: https://www2.physics.ox.ac.uk/sites/default/files/profiles/proud/him8-meteor-44706.gif
https://twitter.com/simon_sat/status/1108120937059282945

<a href="http://www.youtube.com/watch?v=5bkiXnWIKtQ" target="_blank">http://www.youtube.com/watch?v=5bkiXnWIKtQ</a>
https://www.youtube.com/watch?v=5bkiXnWIKtQ


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