Asteroid 2017 AG13 was only spotted by scientists at the last minute.
On Monday, while you were watching Meryl Streep's viral Globes speech or doing whatever else to fill the void, planet Earth came dangerously close to being hit by a small asteroid. Asteroid 2017 AG13—as it has since been dubbed—is roughly the size of a multi-storey apartment building, and just scraped by without making contact with the planet we're living on. And, somewhat disturbingly, scientists only realised it was coming at the very last minute.
Travelling at a relative velocity of more than 57,600 kilometres per hour, the asteroid missed Earth by about 160,000 kilometres. Which may sound like a lot, but it's actually a bit too close for comfort. It's two times closer than the distance between the Earth and the moon.
AG13 was spotted over the weekend by astronomers at the Slooh Observatory, who organised a last minute live broadcast of the fly-by. So there was only a two-day buffer between us knowing about the asteroid, and the asteroid passing us by. For reference, NASA scientists had an 18-day asteroid warning in the movie Armageddon.
While the space rock wasn't large enough to destroy the planet, or require the services of Bruce Willis, it would likely have caused significant damage to whatever populated area it hit. In 2013, the Russian town of Chelyabinsk was hit by a fireball, blowing out windows and causing thousands of minor injuries.
So why wasn't AG13 spotted? Well, the asteroid was about half the size of those that are usually detected by NASA's infrared telescope Near Earth Object Camera (NEOCam), which is designed to search the skies for potentially devastating asteroid threats. The NEOCam program is currently operating only with limited funding, with NASA choosing to instead prioritise asteroid exploration missions on Jupiter.
If the imminent threat of space rock destruction worries you, check out the official White House strategy on detecting and deflecting asteroids here. As the document outlines, "in an ideal situation, an Earth-bound NEO can be deflected or disrupted well before it reaches Earth" but "scenarios may occur in which a NEO impact cannot be prevented because there is not enough time between detection and impact to deflect or disrupt it."
Unfortunately, asteroid detection funding is so low that asteroids the size of AG13 will continue to go undetected by NASA. Which sucks, because they can potentially cause major harm to cities. As for the Armageddon-sized NEOs, well—we'll probably see them coming, but the question of when will determine how well we can respond.
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