THE United States Air Force detected a massive explosion in December of last year when an asteroid blew up in our atmosphere.
The blast was ten times more powerful than the explosion from the atomic bomb that devastated Hiroshima, and had not been predicted.
AP:Associated Press The meteor would have looked very much like this blast seen over Chelyabinsk in 2013
It hit at around midday local time — but because the impact happened over the Bering sea it was not widely noticed.
The rock, several metres across, burned through the upper atmosphere at 72,000 miles per hour before exploding 16 miles up.
It was the most powerful such explosion since a huge blast rocked the Russian region of Chelyabinsk in 2013.
Talking to BBC News, Lindley Johnson, planetary defence officer at Nasa said that a fireball this big is only expected about two or three times every 100 years.
The 173-kiloton explosion was 40 per cent as powerful as the Chelyabinsk blast, but came dangerously close to routes used by major airlines.
Many flights between the USA and Asia fly over the Bering Sea, and researchers have reached out to airlines to see if anyone actually saw the blast.
NASA tracks a number of so-called Near Earth Objects, but didn’t have this one on their scopes.
In fact, Johnson revealed that NASA only found out about the impact when they were informed by the US Air Force, whose detection systems had picked up the massive explosion.
The 2013 Chelyabinsk meteor laid bare the planet’s vulnerability after nobody saw it coming
Nasa believes none of the thousands of NEOs that it keeps a close eye on are currently on a collision course with our planet.
“Nasa knows of no asteroid or comet currently on a collision course with Earth, so the probability of a major collision is quite small,” it says.
“In fact, as best as we can tell, no large object is likely to strike the Earth any time in the next several hundred years.”
In March, two 100-foot asteroids zipped past us under Nasa’s watchful eye.
While an asteroid that big could cause major local damage around an impact site, it would need to be about twenty times that size to cause problems on a global scale.
Last month, Nasa released its best photos of yet of a potential doomsday asteroid known as Bennu.
What’s the difference between an asteroid, meteor and comet?Here’s what you need to know, according to Nasa…
Asteroid: An asteroid is a small rocky body that orbits the Sun. Most are found in the asteroid belt (between Mars and Jupiter) but they can be found anywhere (including in a path that can impact Earth)
Meteoroid: When two asteroids hit each other, the small chunks that break off are called meteoroids
Meteor: If a meteoroid enters the Earth’s atmosphere, it begins to vapourise and then becomes a meteor. On Earth, it’ll look like a streak of light in the sky, because the rock is burning up
Meteorite: If a meteoroid doesn’t vapourise completely and survives the trip through Earth’s atmosphere, it can land on the Earth. At that point, it becomes a meteorite
Comet: Like asteroids, a comet orbits the Sun. However rather than being made mostly of rock, a comet contains lots of ice and gas, which can result in amazing tails forming behind them (thanks to the ice and dust vapourising)
As with the Chelyabinsk blast, no-one saw this one coming.
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