The asteroid, dubbed 2019 OK, brushed past our planet on July 25 but the rock was not spotted until it closed-in on Earth. NASA later confirmed the asteroid skimmed the planet from a dangerously close distance of just 40,400 miles – one-fifth of the distance to the Moon. A similar surprise in 2013 resulted in a rogue space rock inuring more than 1,000 people with shards from blown-out windows in Russia. Internal NASA emails obtained by BuzzFeed reveal the US space agency was completely caught off-guard by 2019 OK.
One NASA employee admitted “this one did sneak up on us” while it flew past Earth at speeds of 23km per second or 52,568mph.
Planetary defence officer Lindley Johnson informed NASA of the close approach on July 24, 24 hours before the asteroid’s arrival.
He wrote in his internal memo: “Because there may be media coverage tomorrow, I’m alerting you that in about 30 mins a 57-130 meter sized asteroid will pass Earth at only 0.19 lunar distances (~48,000 miles).2019 OK was spotted about 24 hrs ago.”
Paul Chodas of NASA’s Jet Propulsion Laboratory later wrote in an email the asteroid had slipped through the net.
READ MORE: How often do asteroids hit Earth? What is the danger
Measuring between 187ft and 426.5ft (57m and 130m) in diameter, the asteroid was detected by the Southern Observatory for Near Earth Asteroids Research in Brazil.
Mr Chodas said: “This object slipped through a whole series of our capture nets.
“I wonder how many times this situation has happened without the asteroid being discovered at all.”
Weeks after the planet’s close brush with cataclysm, NASA confirmed the rock packed enough power to wipe out an entire city.
READ MORE: There is a slim chance a 2,700 MEGATON asteroid might hit Earth this October
In a press release on August 6, the US space agency 2019 OK was the largest asteroid to pass this close to Earth in a century.
The asteroid was compared in size to a football field.
According to NASA’s Center for Near Earth Object Studies, the asteroid was missed due to various unfortunate factors.
Firstly, the rock came in from an orbit that is not fully observable by Earth’s telescopes.
Secondly, the asteroid’s movement was not visible enough against the backdrop of glowing stars to spot its approach.
READ MORE: Expert reveals Earth experiences a ‘near-miss’ on a ‘monthly basis’
Mr Chodas said: “An asteroid of this size coming this close to Earth is a pretty rare event – on the order of about twice a century.
“And an impact by an asteroid of this size is rare still, on average only on the order of once every several thousand years.”
Thankfully, NASA confirmed the July flyby was the closest the asteroid will come to Earth for another 200 years.
The approach did, however, highlight the need for better ground and space-based detections systems.
A space expert recently told Express.co.uk NASA’s efforts to protect the Earth are “interesting” but not enough.
Quick facts about asteroids, comets and meteors:
1. Some of the bigger space rocks in the Asteroid Belt can be as large as 583 miles across.
2. NASA estimates a football field-size asteroid collides with our planet once every 2,000 years or so.
3. A car-sized asteroid hits the Earth on average at least once a year.
4. A meteor that survives the fiery descent through Earth’s atmosphere is known as a meteorite.
5. As icy comets fly around the solar system, their outer layers sublimate in the Sun’s heat and leave behind a glowing trail.