A huge asteroid just missed Earth — and we didn’t see it coming. It was the closest miss in recorded history.

On April 15, 2018, a soccer pitch-sized asteroid missed crashing into Earth. The asteroid known as 2018 GE3, was the largest asteroid ever to buzz the Earth, and it hurtled past at 66,000 mph. So why didn’t anyone see this massive rock coming?

Source: https://www.vice.com

At 2 AM on Sunday morning, April 15, 2018 (AEST time) astronomers at the Steward Observatory Catalina Station in Arizona spotted an asteroid hurtling towards Earth at 106,497 km/h. Called 2018 GE3, it was estimated to be up to 110 meters in diameter, which is the same length as an average FIFA soccer field. Scientists quickly calculated that it would pass us the following day, but only just. And actually 2018 GE3 would turn out to be the largest known asteroid to ever drift so close to Earth, and this particular rock’s first visit since 1930.

The next day it tore past without incident, brushing within 192,317 km of our upper atmosphere. And sure, that sounds like a healthy margin for error, but keep in mind that space is infinite and the moon is just 400,000 kilometers away.

So what would have happened if it’d hit us? Well, as a fun game of comparative speculation, the meteorite that exploded over remote forest in Russia in 1908, known as the the Tunguska event, is thought to have been between 60 to 190 metres in diameter. It didn’t kill anyone, but that’s only because the area was basically unpopulated. And it did flatten about 200 kilometers of pine trees.

Notably, the other meteorite that blew up over Russia—the 2013 Chelyabinsk meteor—was only 20 metres in diameter. And according to state media, that put some 1,500 people in hospital after the shock wave showered residents in broken windows.

So the next question: why the hell didn’t anyone see 2018 GE3 coming sooner?

According to Livescience, the issue is that asteroids are dark and small, while the sky is huge. As they note, the most common variety of asteroids are composed of rock that doesn’t reflect light, making them hard to spot. Telescopes need to be pointed at just the right patch of sky at just the right time to see them, which requires dozens of telescopes operating simultaneously to monitor the sky.

NASA does actually operate an asteroid detection program, aptly called Planetary Defense. As their website explains, they are “ensuring the early detection of potentially hazardous objects asteroids and comets,” while also “leading the coordination of U.S. Government planning for response to an actual impact threat.”

The observatory that detected 2018 GE3 did notify NASA, but it was determined to not be a threat. And as you’d know by being able to read this, they were right. Just.

This article originally appeared on VICE AU.

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Source: https://www.sciencealert.com

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NASA Basically Missed a Huge Asteroid That Passed Unnervingly Close to Earth

We only had a few hours of warning.

While the world was busy doing its thing on Saturday, a giant asteroid the size of a football field whizzed by our planet.

NASA scientists noticed the massive asteroid at an observatory in Arizona just a few hours before it gave Earth a surprise flyby.

A mere 21 hours after that initial sighting, Asteroid 2018 GE3 came a little too close for comfort.

Travelling around 106,000 kilometres per hour (66,000 miles per hour) the asteroid was as far away from Earth as half the average distance between Earth and the Moon.

And while that may sound far away, in space-terms, that’s spine-chillingly close.

 

The situation is especially terrifying when considering the sheer size of the asteroid.

Once or twice a week, scientists will notice an asteroid that gets closer than the distance to the Moon.

The difference is, those asteroids are usually about the size of a bus, or maybe a house. Asteroid 2018 GE3 was more like the size of Walmart.

NASA has estimated that Asteroid 2018 GE3 is somewhere between 47 to 100 metres (157 to 360 feet) wide.

 That means the asteroid was roughly 3.6 times the size of the one that cleared 2,000 square kilometres (500,000 acres) of Siberian forest in 1908.

And that particular asteroid was estimated to have produced about 185 times more energy than the Hiroshima atomic bomb.

NASA’s website describes the event like this:

A man is sitting on the front porch of a trading post at Vanavara in Siberia. Little does he know, in a few moments, he will be hurled from his chair and the heat will be so intense he will feel as though his shirt is on fire.

That’s how the Tunguska event felt 40 miles [64 kilometres] from ground zero.

It’s not fun to imagine what would have happened if Asteroid 2018 GE3 had found its way to Earth.

“If 2018 GE3 had hit Earth, it would have caused regional, not global, damage, and might have disintegrated in the atmosphere before reaching the ground,” SpaceWeather.com reported.

“Nevertheless, it is a significant asteroid, illustrating how even large space rocks can still take us by surprise. 2018 GE3 was found less than a day before its closest approach.”

 Asteroids are small and dark so they are notoriously difficult for scientists to pick up. Plus, they move really quickly, which means a telescope needs to be pointed in just the right spot at just the right time to catch them.

Luckily, NASA has a program for asteroid detection, although the program tends to only scan for asteroids that are 140 metres (460 feet) wide. Even at the highest estimate, the 2018 GE3 was only about three-fourths that size.

Still, it doesn’t take much for an asteroid to cause damage here on Earth. In 2013, an asteroid that was about three to six times smaller than 2018 GE3 injured more than 1,200 people and damaged thousands of buildings in Chelyabinsk, Russia.

At least for now, we can all breathe a sigh of relief.

 

 

 

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