Astronomers have been keeping their eyes on a 1,200 foot wide chunk of space rock that has been hanging around the neighborhood lately. It’s an asteroid called Apophis, and it’s named for an ancient Egyptian spirit who was bent on plunging the world into eternal darkness. Scientists are concerned because this modern incarnation may succeed where its namesake failed.

In 2004 NASA gave Apophis a 1-in-37 chance of hitting the Earth in 2029, but after further observations of its path through space, NASA recently revised the odds to a 1-in-5,500 chance of colliding in 2036. Such an event, though unlikely, would cause an explosion about 100,000 times more powerful than the Hiroshima bomb and throw huge amounts of dust into the atmosphere, posing a grave risk to any humans who manage to survive the Avian Flu.

Scientists are now urging world governments to decide on a strategy for preventing the potential impact. Experts in near-Earth objects (NEOs) warn that it would take decades to design, test, and build technology to deflect or destroy a substantial asteroid. According to Monica Grady, an expert in meteorites at Open University, “It’s a question of when, not if, a near Earth object collides with Earth. Many of the smaller objects break up when they reach the Earth’s atmosphere and have no impact. However, a NEO larger than 1km [wide] will collide with Earth every few hundred thousand years and a NEO larger than 6km, which could cause mass extinction, will collide with Earth every hundred million years. We are overdue for a big one.”

Update: In 2021 scientists’ new models suggest that the Earth is safe from Apophis for at least 100 more years.