Scientists worldwide mark first annual Asteroid Day with stark warnings

Scientists around the world held what they billed as the first annual Asteroid Day on Tuesday, giving lectures and hosting panel discussions promoting projects designed to detect threats from space before it’s too late.

The scientists who organized the events said humans must do a better job searching for asteroids because even a relatively small one — about the size of a house — could level a city and kill millions of people.

As it orbits the sun, the Earth encounters tons of tiny space rocks every day. Most burn up in the atmosphere, but larger objects occasionally make it to the surface or near it.

“What we’re trying to do with planetary defense is, at a minimum, we can evacuate people” from the potential impact area, Rusty Schweickart, an Apollo 9 astronaut who has pushed for better preparedness, said at an Asteroid Day event at the California Academy of Sciences in San Francisco.

Potentially civilization-ending asteroids — miles-wide ones that could scorch continents and blast dust into the sky, blotting out the sun for decades — hit only once every tens of millions of years, he said, noting the 7-mile-wide object whose impact is thought to have caused the extinction of the dinosaurs 66 million years ago, starving them beneath a pall of choking ash.  

But what worries the former astronaut isn’t this type of giant, which space scientists have been successful in tracking, with many concluding they pose no imminent threat. Shweickart is more afraid of the smaller ones, like the object that injured 1,500 people in the Russian city of Chelyabinsk on Feb. 15, 2013. 

That object, about the size of a two-story house, exploded in the atmosphere with the power of 30,000 Hiroshima bombs and lit up the dawn sky with a flare as intense as the sun. Most injuries were caused by flying debris and broken glass from windows. 

There are 10 million such asteroids, he said, adding that we know the locations of only one-tenth of 1 percent of them. Astronomers missed the Chelyabinsk object before its arrival. 

“The odds are, if one of them hit, we wouldn’t have known about it,” he said, stressing that this is “not an academic exercise” because such objects strike relatively frequently — about once every 50 years.

More damaging are objects slightly bigger than the Chelyabinsk object, more like the rock that exploded in the air over the remote Tunguska region of Siberia on June 30, 1908, leveling hundreds of square miles of trees. Asteroid Day marks the anniversary of that sobering event.

Had that blast occurred over Moscow — less than an eyelash away in the scale of space — it would have completely destroyed the city.

What’s needed, activists and scientists say, is more satellites and telescopes scanning the stars for smaller objects that sometimes come hurtling at us from behind the glare of the sun. 

One proposal is the Sentinel mission, which would send a craft to orbit the sun, not the Earth, and follow the orbit of Venus to track such objects. It would stay on the opposite side of the solar system from Earth so that its telescope could look away from the brightness of our home star. 

Advocates for more research have signed the 100X Declaration, an online petition that urges governments to do a better job finding dangerous space objects. It calls for a massive increase in the effort, “a rapid hundredfold acceleration of the discovery and tracking of near-Earth asteroids to 100,000 per year within the next 10 years.” 


The declaration, meant to raise awareness among political leaders and philanthropists, was issued in December 2014 and has gained the signatures of public figures such as Bill Nye and Richard Dawkins.

“Our surveillance of near-Earth objects is not good enough, so we are trying to ramp up the rate of detection by 100 times,” Brian May, an astrophysicist and a former guitarist for the rock band Queen, said in a statement. 

“Signing the 100X Declaration is a way for the public to contribute to bringing about an awareness that we can protect humanity now and for future generations," he added.