The largest fireball since the Chelyabinsk blast in February 2013 has been revealed, detected onFebruary 6 at 2 p.m. UTCin the South Atlantic Ocean.But this eventhappened in the middle of the ocean, about 1,850 kilometers (1,150 miles) south-east of Rio de Janeiro in Brazil, so it likely wasn’t seen directly or caught on camera.
Data released by NASA shows that themeteor released an energy equivalent to 12,000 tonnes (13,000 tons) of TNT, and it was moving at over 15.5 kilometers per second(9.6 miles per second). It disintegrated at a height of about 31 kilometers (19 miles) and it had a diameter of about 7 meters (23 feet), calculated based on itskinetic energy.
While 12,000 tonnes of TNT seems like a very large number, it pales in comparison to theChelyabinsk impact, whichwas 40 times more energetic andreleased450,000 tonnes (500,000 tons) of TNT. The Chelyabinsk event, although not incredibly dangerous in itself, injured over 1,000 people due to windows breaking. If this event had happened over a populated area, it would haveat most rattled some windows and scared a few people, according toPhil Plait at Slate.
Relative location of the fireball. Google Maps
The report and information on the eventwere given to NASA by the U.S. government. Detecting atmospheric explosions is most likely a high priority of several branches of the U.S. military, so a fireball of such magnitude could have been easily picked up. Satellite imagery and infrasoundatmospheric microphones could both be used to detect an impact like this.
These events, although unusual, are not as uncommon as one might think. Meteoroids of about 10 meters (33feet) in diameterhit Earth about once every 10 years, although some argue that it might be closer to a yearly occurrence,and we get hit with much smaller debris every day. NASA has a list of some of the brightest fireballs,the NASA’sFireball and Bolide page, but it’s certainly not an exhaustive list as detection is not easy.
Meteors are made up of fragments of asteroids and comets that impact our planet atmosphere. They burn quickly on their way to the ground and most of them are disintegrated high in the atmosphere. If fragments manage to reach the ground, they are called meteorites.
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