An asteroid almost twice the size of a London bus will zip past Earth tomorrow – and NASA almost missed it.
Known as 2019 TW1, the asteroid is estimated to be up to 16 metres (52ft) wide, and is travelling at roughly 26,000 mph relative to the Earth.
It was first spotted on 5 October – just three days days ahead of its close brush with our planet, according to NASA's Center for Near Earth Object Studies.
Luckily it will pass at a safe distance of 351,000 miles, which is 1.47 times the distance of the Moon.
While this might sound far, it's terrifyingly close in astronomical terms.
It is classified as a near-Earth object (NEO), which is the name NASA gives to space rocks with orbits that allow them to enter the Earth's neighbourhood.
Specifically, 2019 TW1 is classified as an Apollo near-Earth asteroid, which means its path around the Sun crosses Earth's orbit.
It is one of seven NEOs due to zip past the Earth tomorrow – although none of the others will come quite as close.
Several were also only discovered last week – including 2019 TC1, which will pass at a distance of 834,000 miles, and 2019 TU, at a distance of just over 1 million miles.
The largest, 2019 RK, is about the size of the Arc de Triomphe, and only slightly smaller than the famous Chelyabinsk meteor that exploded in the sky over Russia in 2013.
More than 1,500 people were injured in the impact, and 7,200 buildings damaged by the shock wave that rippled out for hundreds of miles.
Luckily 2019 RK will pass at a distance of almost 4 million miles, so there's no chance if it hitting.
However, it is concerning that so many NEOs are being spotted only days before they are due to make a close approach to Earth.
Earlier this year, an asteroid large enough to wipe out a city came within 45,000 miles of Earth – the astronomical equivalent of a near-miss.
"This one did sneak up on us," Lindley Johnson, NASA's planetary defence officer, told colleagues the day after the 55,000mph fly-by on July 25.
"It is an interesting story on the limitations of our survey network," she wrote in an email obtained as part of a freedom of information request by Buzzfeed News .
If the space rock had entered Earth's atmosphere, the resulting blast wave would have devastated an area about 50 miles across, NASA said.
This is why NASA is investing $600 million (480 million) in a new space telescope that will survey the sky for potentially hazardous asteroids.
The new telescope could launch as soon as 2025, and will enable NASA to find 90% of as-yet-undiscovered NEOs that have a chance of hitting the Earth within 10 years.
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