Largest fireball since Chelyabinsk falls into the ocean: Nasa reports huge explosion of seven meter
A huge fireball crashed into the Atlantic earlier this month - and went almost unseen.
The event took place on February 6 at 14:00 UTC when a meteor exploded in the air 620 miles (1,000km) off the coast of Brazil.
It released energy equivalent to 13,000 tons of TNT, which is the same as the energy used in the first atomic weapon that leveled Hiroshima in 1945.
This was the largest event of its type since the February 2013 fireball that exploded over Chelyabinsk, Russia, leaving more than 1,600 people injured.
That fireball measured 18 meters across and screamed into Earth's atmosphere at 41,600 mph. Much of the debris landed in a local lake called Chebarkul.
The Chelyabinsk fireball had 500,000 tons of TNT energy - 40 times more than the latest impact, according to Phil Plait.
‘As impacts go, this was pretty small,’ Plait writes in an in-depth report in his Slate blog. ‘After all, you didn’t even hear about until weeks after it occurred.
‘Had it happened over a populated area it, would’ve rattled some windows and probably terrified a lot of people, but I don’t think it would’ve done any real damage.’
Ron Baalke, who works for Nasa, first tweeted the event after it appeared on the space agency’s Near-Earth Object Fireball page.
Plait estimates that, given the explosive energy of the most recent fireball, it was likely to be around five to seven meters wide.
It is believed to have exploded about 18 miles (30km) above the Atlantic Ocean, 6 miles above the troposphere, the atmospheric layer where the Earth's weather occurs.
It is unlikely that anyone saw it, but it was probably picked up by the military, who record atmospheric explosions.
‘Impacts like this happen several times per year on average, with most going unseen,’ Plait said.
It’s the much larger impacts that we should be worried about.
Nasa tracks around 12,992 near-Earth objects which have been discovered orbiting within our solar system close to our own orbit.
It estimates around 1,607 are classified as Potentially Hazardous Asteroids.
In September, Paul Chodas, manager of Nasa's Near-Earth Object office at the Jet Propulsion Laboratory in Pasadena, said: 'There is no existing evidence that an asteroid or any other celestial object is on a trajectory that will impact Earth.
'In fact, not a single one of the known objects has any credible chance of hitting our planet over the next century.
One such asteroid is 2013 TX68, which poses no threat to Earth, but could get very close to the surface, according to the space agency – although it adds there is a very slim chance of this happening.
While the March 5th asteroid poses no threat, scientists have long said that these space rocks could threaten life on Earth.
Last year, Brian Cox said we are at risk of being wiped out by asteroids – and we're not taking the threat seriously.
'There is an asteroid with our name on it and it will hit us,' Professor Cox told DailyMail.com. In fact, the Earth had a 'near-miss' only a few months ago.
'We didn't see it,' says the 46-year-old. 'We saw it on the way out, but if it had just been a bit further over it would have probably wiped us out. These things happen.'
The bus-sized asteroid, named 2014 EC, came within 38,300 (61,637km) miles of Earth in March - around a sixth of the distance between the moon and our planet.
And it wasn't the only one threatening Earth. Nasa is currently tracking 1,400 'potentially hazardous asteroids' and predicting their future approaches and impact probabilities.
The threat is so serious that former astronaut Ed Lu has described it as 'cosmic roulette' and said that only 'blind luck' has so far saved humanity from a serious impact.
The 100ft-wide asteroid, first spotted when it flew by Earth two years ago, will make its return On March 5 – and this time it could get incredibly close.
The whale-sized space rock may skim past Earth at just 11,000 miles (17,000 km), which is around 21 times closer to Earth than the moon.
But Nasa admits this estimate may be widely inaccurate, and the asteroid may also pass Earth as far out as 9 million miles (14 million km).
'The variation in possible closest approach distances is due to the wide range of possible trajectories for this object, since it was tracked for only a short time after discovery,' Nasa explained.
Scientists have identified an extremely remote chance that this small asteroid could impact on September 28, 2017, with odds of no more than 1-in-250-million.
Flybys in 2046 and 2097 have an even lower probability of impact.
'The possibilities of collision on any of the three future flyby dates are far too small to be of any real concern,' said Paul Chodas, manager of CNEOS.
'I fully expect any future observations to reduce the probability even more.'
Asteroid 2013 TX68 is estimated to be about 100ft (30 meters) in diameter.
If an asteroid the size of 2013 TX68 were to enter Earth's atmosphere, it would likely produce an air burst with about twice the energy of the Chelyabinsk event.
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