A few months ago, on December 18, 2018, a massive aerial explosion in the heavens above the Earth exploded with the equivalent of 173 kilotons of TNT.
This is more than 10 times the amount released by the bombings of Hiroshima (15 kilotons) and the third largest meteor explosion in more than 100 years, behind the Chelyabinsk explosion in 2013 (440 kilotonnes) and the Tunguska event in 1908 (at least 3 megatons). .
How on earth is there such an explosion? Well, there was no one around us to watch this happen.
It exploded above the clouds above the Bering Sea, close but not far enough from the nearest country, the Russian Kamchatka Peninsula.
A meteor that explodes in a fireball in midair is also called a racing car.
According to researcher meteorologist Peter Brown of Western University in Canada, the event was detected by at least 16 infrasound stations around the world, a global network designed to monitor the planet from atmospheric nuclear explosions (but which can also detect events such as earthquakes, volcanic eruptions and, yes, cars).
"When you see these infrasonic waves, you immediately know that there has been a significant impact or release of energy," said astronomer Alan Fitzsimmons of Queen's University & # 39; in Belfast. New scientist.
NASA scientists independently received information on the explosion from US military satellites, which detected visible and infrared light from the car.
In addition, the Japanese weather satellite Himawari-8 captured its trail of smoke by chance as the meteor fell.
Some color views of #meteor which flew over the North Pacific in December 2018, taken by Japan #Himawari Satellite.
The meteor is really clear here – bright orange fireball on the blue + white background!
Background: https://t.co/r403SQxicZ pic.twitter.com/ctNN8zxsXb
– Simon Proud (@simon_sat) March 18, 2019
According to military data, NASA scientists were able to calculate that the meteor had passed through the atmosphere at a speed of about 115,200 kilometers at the time (71,600 miles to the US). Hour), at a steep angle of 7 degrees, and that it had exploded at an altitude of 25.6 kilometers (16 miles).
On the basis of infrasound data, Brown could deduce that the meteor had a diameter of about 10 meters (33 feet) and a mass of about 1400 tons.
This figure is far below the lower limit of 140 meters of potentially dangerous Earth-like asteroids that NASA hopes to detect – but the Chelyabinsk meteor was also 20 meters away.
When it exploded at an altitude of 23.3 km above Russia in 2013, the explosion damaged buildings of several hundred kilometers, mainly due to broken windows, and about 1,200 people were injured, but no deaths were reported.
The Tunguska event destroyed an area of the Siberian forest of about 2,000 square kilometers (770 square miles).
Hello, fantastic post on the meteor.
I quickly checked MODIS-Terra …. they seem to have had a pass at the right time (an amazing coincidence!). I have cropped the 250m res below or check the link.https: //t.co/JJskoBkPFL pic.twitter.com/ctgB9yEcsy
– Giorgio Savini (@UCLOAstroSphinx) March 18, 2019
Thus, although these events occur less than a few times a century (and it is only a coincidence that the most important events took place in Russia), they can be incredibly destructive if they occur over land.
We are lucky that the surface of the Earth is mainly made up of sea. Car bombs bursting harmlessly over the ocean are certainly not unknown. For example, a 12-kiloton TNT powerboat exploded off the coast of Brazil in 2016, as military satellite data post-event still reveals.
In fact, NASA has listed 774 atmospheric fireballs since 1988 at the time of writing, most of which occurred over the ocean.
It is estimated that millions of meteors enter the Earth 's atmosphere each day. The vast majority of them are tiny and burn at the entrance to the atmosphere, but a few are big enough to explode – the larger the meteor, the bigger the boom is.
Those that are large enough to cause a detectable event by satellites and infrasound stations are relatively rare in comparison.
The Bering Sea car exploded near a flight path of a commercial airline between North America and Asia, and NASA therefore appealed to the companies concerned for all observations of the event. If we are really lucky, there may even be photos!