‘This one did sneak up on us’: Internal NASA emails reveal how it almost ‘missed’ a football-field-sized asteroid that skimmed the Earth.

• Scientists announced the asteroid discovery just hours before its close approach
• Asteroid 2019 OK was about 100 metres wide and came within 70,000 km of Earth
• At its closest approach in July, it was closer to Earth than the moon
• Experts say impact from object of this size would be enough to ‘devastate a city’

Published: 11:59 BST, 20 September 2019 | By Sam Blanchard For Mailonline An asteroid which had a ‘close pass’ with Earth in July had not been picked up by NASA before it swept past. Internal emails have revealed the US space agency was caught by surprise by the asteroid named ‘2019 OK’. It passed about 40,400 miles away from Earth, still a harmless distance, but was the largest rock to have done so in almost 100 years. Emails obtained through Freedom of Information revealed one NASA staffer telling colleagues the asteroid had ‘slipped through the net’. Travelling at 55,000mph and measuring 426 feet by 187ft (57m x 130m), NASA only realised 2019 OK was coming 24 hours before it passed. Buzzfeed News revealed internal emails from the space agency which saw staff there giving one another the heads up that they might be asked about it. One, from NASA’s planetary defense officer, Lindley Johnson, said: ‘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 After the asteroid had passed a news release warned that it could have destroyed an area measuring 50 miles across, something which only happens about once every 3,000 years. NASA’s Paul Chodas wrote in an email two days after 2019 OK had passed: ‘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.’ The emails seen by Buzzfeed showed how NASA scrambled to work out why it hadn’t seen the asteroid before it was so close. At its closest point the space rock, which was so large that experts had dubbed it a ‘city killer’, was closer to Earth than the moon is.

WHAT ARE THE DIFFERENT TYPES OF SPACE ROCKS?

An asteroid is a large chunk of rock left over from collisions or the early solar system. Most are located between Mars and Jupiter in the Main Belt. A comet is a rock covered in ice, methane and other compounds. Their orbits take them much further out of the solar system. A meteor is what astronomers call a flash of light in the atmosphere when debris burns up. This debris itself is known as a meteoroid. Most are so small they are vapourised in the atmosphere. If any of this meteoroid makes it to Earth, it is called a meteorite. Meteors, meteoroids and meteorites normally originate from asteroids and comets. For example, if Earth passes through the tail of a comet, much of the debris burns up in the atmosphere, forming a meteor shower. Read more on ExpressInformer.com