Image copyright Getty Images Image caption Artwork: The fireball was the kind of event expected to happen only two to three times per century

A huge fireball exploded in the Earth's atmosphere in December, according to Nasa.

The blast was the second largest of its kind in 30 years, and the biggest since the fireball over Chelyabinsk in Russia six years ago.

But it went largely unnoticed until now because it blew up over the Bering Sea, off Russia's Kamchatka Peninsula.

The space rock exploded with 10 times the energy released by the Hiroshima atomic bomb.

Lindley Johnson, planetary defence officer at Nasa, told BBC News a fireball this big is only expected about two or three times every 100 years.

What do we know?

At about noon local time on 18 December, the asteroid barrelled through the atmosphere at a speed of 32km/s (20 miles per second) , on a steep trajectory of seven degrees.

Measuring several metres in size, the space rock exploded 25.6km above the Earth's surface, with an impact energy of 173 kilotons.

"That was 40% the energy release of Chelyabinsk, but it was over the Bering Sea so it didn't have the same type of effect or show up in the news," said Kelly Fast, near-Earth objects observations programme manager at Nasa.

"That's another thing we have in our defence, there's plenty of water on the planet."

Dr Fast was discussing the event here at the 50th Lunar and Planetary Science Conference in The Woodlands, near Houston, Texas.

Military satellites picked up the blast last year; Nasa was notified of the event by the US Air Force.

Dr Johnson said the fireball came in over an area not too far from routes used by commercial planes flying between North America and Asia. So researchers have been checking with airlines to see if there were any reported sightings of the event.

What's the significance?

In 2005, Congress tasked Nasa with finding 90% of near-Earth asteroids of 140m (460ft) in size or larger by 2020. Space rocks of this size are so-called "problems without passports" because they are expected to affect whole regions if they collide with Earth. But scientists estimate it will take them another 30 years to fulfil this congressional directive.

Image copyright NASA Image caption Artwork: The NeoCam concept would aim to discover many of the undiscovered asteroids above 140m in size

The meteor trail was seen by Nasa's Terra satellite

Once an incoming object is identified, Nasa has had some notable success at calculating where on Earth the impact will occur, based on a precise determination of its orbit.

In June 2018, the small 3m (10ft) asteroid 2018 LA was discovered by a ground-based observatory in Arizona eight hours before impact. The Center for Near-Earth Object Studies at Nasa's Jet Propulsion Laboratory (JPL) then made a precision determination of its orbit, which was used to calculate a probable impact location. This showed the rock was likely to hit southern Africa.

Just as the calculation suggested, a fireball was recorded over Botswana by security camera footage on a farm. Fragments of the object were later found in the area.

Image copyright Himawari/JMA/Simon Proud/Oxford Uni Image caption Japan's Himawari satellite captures the fireball's steep descent

Media playback is unsupported on your device Media caption Archive: Eyewitnesses and CCTV cameras captured the moment the Chelyabinsk meteor flew across the sky

How can monitoring be improved?

The latest event over the Bering Sea shows that larger objects can collide with us without warning, underlining the need for enhanced monitoring.

A more robust network would be dependent not only on ground telescopes, but space-based observatories also.

A mission concept in development would see a telescope called NeoCam launched to a gravitational balance point in space, where it would discover and characterise potentially hazardous asteroids larger than 140m.

Dr Amy Mainzer, chief scientist on NeoCam at JPL, said: "The idea is really to get as close as possible to reaching that 90% goal of finding the 140m and larger near-Earth asteroids given to Nasa by Congress.

She said that if the mission did not launch, projections suggested it would "take us many decades to get there with the existing suite of ground-based surveys".

Dr Mainzer added: "But if you have an IR-based (infrared) telescope, it goes a lot faster."

Follow Paul on Twitter.</s>NASA has reported that a large meteor explosion over the Bering Sea, near Russia's Kamchatka Peninsula in December 2018 went unnoticed despite being second in power over the last 30 years of observations. The Bering Sea fireball exploded 25.6 kilometres above the air having struck thicker layers of the atmosphere with its air burst power reaching 173 kilotons, which is 11 times less than "Little Boy", a 15-kiloton bomb that was dropped on Hiroshima.

The meteor entered the Earth's atmosphere almost vertically at a steep angle of 7 degrees and at a speed of around 32km/s. It remained at first unnoticed by NASA, but the agency was later notified by the US Air Force about the blast.

Despite producing the second powerful air burst in 30 years, the Bering Sea meteor went largely unnoticed as it exploded over the sea and not above an inhabited area as happened with the Chelyabinsk meteor in 2013, which produced the most powerful meteor air burst over the last 30 years. Back then social media was flooded with videos and photos of the fireball blazing in the sky brighter than sun. The superbolide exploded around 30 kilometres above the Earth with a power of 400 to 500 kilotons, although most of it was sucked by the thick atmospheric layers.

READ MORE: WATCH Meteor Streak Through Sky Above Mexico City

Still, the 2013 airburst damaged thousands of buildings in the Russian city and collapsed a roof of one factory.</s>The explosion of a meteorite recorded above the Bering Sea in December was ten times more powerful than the atomic bomb dropped on Hiroshima in 1945, NASA revealed on Monday.

It was the second most powerful event of this kind in the past 30 years, according to NASA data.

Nearly 800 fireball explosions have been recorded inside Earth's atmosphere since 1988 but despite its size, the December 18, 2018 example remained largely unnoticed because of its location 25.6 km above the Bering Sea, off the Kamchatka Peninsula, in Russia's far-east.

The meteorite had travelled through the atmosphere at a speed of 32 km/s, on a trajectory of seven degrees. The calculated impact energy was 173 kilotons — more than ten times the 15 kilotons unleashed by the atomic bomb dropped on the Japanese city of Hiroshima on August 6, 1945.

It was picked up by satellites owned by the US military, which then notified NASA.

Lindley Johnson, planetary defence officer at NASA, told the BBC that the fireball came close to commercial flight routes between North America and Asia and that airlines had been contacted to check if there had been any sightings.

Simon Proud from the University of Oxford, in Britain, has since released some pictures taken by Japan's Himawari satellite, which show a small orange object above the clouds.

The largest explosion of the past 30 years was recorded on February 15, 2013, around 23 km over the Russian city of Chelyabinsk, injuring 1,500 people and damaging thousands of buildings.</s>The entrance and subsequent explosion of the meteor went unnoticed by media and locals in December 2018 as it went off over the sea, far away from inhabited areas.

NASA has reported that a large meteor explosion over the Bering Sea, near Russia’s Kamchatka Peninsula in December 2018 went unnoticed despite being second in power over the last 30 years of observations. The Bering Sea fireball exploded 25.6 kilometers above the air having struck thicker layers of the atmosphere with its air burst power reaching 173 kilotons, which is 11 times less than “Little Boy”, a 15-kiloton bomb that was dropped on Hiroshima.

The meteor entered the Earth’s atmosphere almost vertically at a steep angle of 7 degrees and at a speed of around 32km/s. It remained at first unnoticed by NASA, but the agency was later notified by the US Air Force about the blast.



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Despite producing the second powerful air burst in 30 years, the Bering Sea meteor went largely unnoticed as it exploded over the sea and not above an inhabited area as happened with the Chelyabinsk meteor in 2013, which produced the most powerful meteor air burst over the last 30 years. Back then social media was flooded with videos and photos of the fireball blazing in the sky brighter than sun.

The superbolide exploded around 30 kilometers above the Earth with a power of 400 to 500 kilotons, although most of it was sucked by the thick atmospheric layers.

Still, the 2013 airburst damaged thousands of buildings in the Russian city and collapsed a roof of one factory.



 Alex Jones delivers the latest insight on the New Zealand terror attack.</s>The powerful meteor blast exploded near Russia’s remote Kamchatka Peninsula, over the open waters of the Bering Sea. Military satellite over the region tracked the meteor blast to around 16 miles (25.6km) above the ground. The incident occurred on December 18 last year, when the fireball entered the atmosphere at breakneck speeds of about 71,582mph or 32km per second. The meteor never reached the ground but NASA estimates the blast was more powerful than the devastating nuclear bomb dropped on Hiroshima on August 6, 1945.

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The meteor’s impact energy stood somewhere in the region of 173 kilotonnes of TNT.

Lindley Johnson, planetary defence officer at NASA, told BBC news events like this only happen once every 100 years or so.

But the meteor impact comes six years after the terrifying Chelyabinsk Meteor incident of February 15, 2013.

The Chelyabinsk Meteor injured more than 1,000 people and damaged more than 7,000 buildings when it erupted over Russia's Chelyabinsk Oblast.

NASA sad the December meteor only measured several meteors across, compared to the 65ft-wide (20m) Chelyabinsk rock.

READ MORE: Asteroid warning: Danger of DEEP IMPACT is 'before us'</s>Meteor blast over Russia's Bering Sea packed 10 times the power of Hiroshima bomb

An explosion packing 10 times the energy released by the Hiroshima nuclear bomb has been detected after a meteor hit the Earth's atmosphere — the second largest blast of its kind in 30 years.

The meteor, which measured several metres in size, passed through the atmosphere and exploded about 25 kilometres above the Earth's surface on December 18 last year.

However, unlike the larger Chelyabinsk meteor, which was captured on dashboard cameras and mobile phones, the event went largely unnoticed by amateur space watchers because it took place over the Bering Sea, the northernmost part of the Pacific Ocean, off Russia's Kamchatka Peninsula.

Military satellites picked up the explosion, which had an impact energy of 173 kilotons — about 10 times the energy of the nuclear bomb dropped on Hiroshima, according to the BBC.

"That was 40 per cent of the energy release of Chelyabinsk, but it was over the Bering Sea, so it didn't have the same type of effect or show up in the news," Kelly Fast, NASA's near-Earth objects observations program manager, told the broadcaster.

The explosion occurred in an area close to commercial flight routes between North America and Asia, the space administration said, prompting researchers to check with airlines for reported sightings.

Meteorologists have also taken to social media to identify purported smoke trails belonging to the meteor, picked up by Japan's Himawari satellite.

"I'm sure it's the meteor trace," University of Oxford meteorologist Simon Proud tweeted, alongside satellite images showing a blip in the atmosphere.

"Much higher than any clouds in that region and too high to be a contrail."

The search for visual confirmation is in stark contrast to the Chelyabinsk meteor, which plunged to Earth is a blinding fireball in 2013, damaging thousands of buildings and showering people with debris and shattered glass.

The explosion sent numerous fireballs crashing into the ground, captured on CCTV, car dashboard cameras and mobile phones, followed by a shockwave that knocked people off their feet.

Researchers believe the asteroid collided with another before hitting Earth.</s>The gigantic meteor came within minutes of slamming into the Earth in December – and we’re only just finding out about it.

According to information just released by NASA, the blast, which occurred on December 18, is the biggest since the fireball over Chelyabinsk in Russia six years ago.



The meteor broke up in the upper atmosphere over the Bering Sea, off Russia's Kamchatka Peninsula, releasing energy equivalent to ten times the atomic bomb detonated at Hiroshima in 1945.

The object, which would have been several metres in diameter, hit the atmosphere at about 32kms (over 71,000 mph) , and exploded around 25.6km (16 miles) above the Earth’s surface.

Kelly Fast, near-Earth objects observations programme manager at NASA, told the BBC: ."That was 40% the energy release of Chelyabinsk, but it was over the Bering Sea so it didn't have the same type of effect or show up in the news.

"That's another thing we have in our defence, there's plenty of water on the planet."</s>While you were living your life on December 18th, 2018, a giant space rock exploded 16 miles above the Earth’s surface, giving off 10 times the energy of the atomic bomb detonated over Hiroshima.

The event is properly called a “fireball,” NASA’s term for “exceptionally bright meteors that are spectacular enough to to be seen over a very wide area.”

With an impact energy of 4.2 kilotons, December’s fireball was the second-most powerful to enter Earth’s atmosphere in 30 years. You may recall the first — it was that huge, blinding fireball that rocked parts of Russia in 2013.

This may sound catastrophic, but images being shared of December’s fireball are actually quite poetic in scale. This atomic, otherworldly force appears as a simple red blip above the clouds.

But you likely didn’t know about it until now, because scientists only just noticed it. That’s because the area where the fireball exploded, over the Bering Sea, is extremely remote.

NASA’s Planetary Defense Officer Lindley Johnson told the BBC such a powerful meteor event only happens a few times every 100 years. (As a side note, “Planetary Defense Officer” is probably as close to a real-life “Avengers” title as you’re gonna get.)

CNN has reached out to NASA for additional comment.

In case you’re not uneasy enough about the reality that flaming extraterrestrial objects are continuously pelting our fragile planet, they do so with alarming regularity.

NASA keeps track of most of the notable fireballs and bolides (a similar astronomical term) that reach Earth. So far in 2019, there have already been five notable fireball events. Don’t worry, though! Most are super tiny.

And if the big one ever comes along to make dinosaurs of us all, NASA’s Planetary Defense Office has our backs.</s>On December 18, 2018, the third largest meteor explosion in the last century occurred and almost no one noticed despite it emitting the equivalent energy of 173 kilotons of TNT – 10 times more powerful than the Hiroshima bomb.

The airburst explosion happened in the skies above the Bering Sea, off Russia’s Kamchatka Peninsula. The event was detected by 16 infrasound monitoring stations around the world, which were established to detect nuclear explosions within the Earth’s atmosphere. Its smoke trail was snapped by the Japanese Himawari-8 weather satellite, which just happened to be photographing that area of the sky at the time.

The Bering Sea meteor reportedly exploded near a commercial airline flightpath between North America and Asia, though no sightings have yet been reported.

“When you see these infrasound waves, you know immediately that there has been an impact or a large release of energy,” astronomer Alan Fitzsimmons of Queen’s University Belfast told New Scientist.

NASA conducted independent research into the event using US military satellites, and was able to determine that the meteor was traveling at some 115,200kph (71,600 miles per hour) and exploded at an altitude of 25.6km (16 miles).

Using the satellite data, it is estimated that the space rock measured some 10 meters (33 feet) in diameter, with a mass of around 1,400 tons, meaning it did not meet NASA’s 140-meter lower limit for asteroids to be classified as dangerous near-Earth objects.

The 2013 Chelyabinsk explosion (440 kilotons) damaged buildings inside a several-hundred-kilometer radius, injuring 1,200 people in the process, though no deaths were reported. The Tunguska event in 1908 (3 megatons) flattened roughly 2,000 square kilometers (770 square miles) of Siberian forest.

NASA has logged 774 atmospheric fireballs since 1988, the vast majority of which exploded harmlessly above the Earth’s oceans.</s>A meteor exploded into a massive fireball over Earth in December last year, but it wasn't noticed by anyone till recently.

The blast was the second-largest of its kind in a century, and the biggest since the fireball over Chelyabinsk in Russia in 2013, New Scientist reported. It went unnoticed largely because of where it blew up: over open seas off the coast of the Kamchatka Peninsula in Russia.

The explosion was ten times as powerful as the Hiroshima atomic bomb, hitting Earth's atmosphere at 5.20 am IST (11.50 pm GMT) on 19 December over the stretch of Pacific Ocean between Russia and Alaska.

"A fireball this big is only expected about two or three times every 100 years," Lindley Johnson, planetary defense officer at NASA, told BBC.

The space rock barrelled through the atmosphere at speeds of 32 km/s, exploding around 25 kilometres above the Earth's surface with a little less than half the energy of the Chelyabinsk meteor explosion six years ago.

"But (this explosion) was over the Bering Sea, so it didn't have the same type of effect or show up in the news," Kelly Fast, manager of the near-Earth objects observations programme at NASA, said.

"That's another thing we have in our defense, there's plenty of water on the planet."

Military surveillance satellites picked up on the blast as it happened, and NASA was notified of the event by the US Air Force. Dr Johnson said that the fireball entered the atmosphere over an area close to routes used by commercial planes from North America to Asia and back. Researchers have been verifying with airlines to see if there were any reported sightings of the event from passengers or the pilots.

The recent incident has uncovered a loophole that NASA is attempting to fix: large-enough space rocks on a collision course with Earth that can affect entire regions on land. This fix is an ongoing project using a combination of ground and space-based telescopes.

In a test of the concept, a telescope called NeoCam will be launched to a gravitational balance point in space. It would then discover and characterise potentially hazardous asteroids larger than 140 m in its field of view.

To get a comprehensive map of all potential threats to Earth, researchers have estimated a couple of more decades through NeoCam and other projects.

"It will take us many decades to get there with the existing suite of ground-based surveys. But if you have an IR-based (infrared) telescope, it goes a lot faster," Amy Mainzer, chief scientist on the NeoCam project, said.

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NASA reports that it has detected a huge meteor explosion in Earth's atmosphere on December 18, 2018, above Russia's Kamchatka Peninsula. The explosion went largely unnoticed due to its location. The explosion, which was ten times more powerful than the atomic bomb dropped on Hiroshima, was the second largest of its kind in 30 years.