There are many threats that face Earth, but there's one that you might not know much about that deserves greater attention – an asteroid impact.
At first, it probably sounds a bit ridiculous. Saving Earth from an asteroid requires you to immediately picture Bruce Willis launching into space to blow it to pieces, but Armageddon this would not be. The threat of an asteroid hitting Earth is very real, and very preventable by less explosive means.
Raising the profile of this threat is the goal of Asteroid Day, a fairly new annual movement (this is its second year) that takes place tomorrow on June 30. Its purpose is to highlight just how much of a threat asteroids are to Earth and what can be done.
“Asteroid Day is an educational global movement that really focuses on raising awareness, making the public aware that there are asteroids out there in space, millions of them, and they pose a threat to our wonderful planet,” Grigorij Richters, the founder of Asteroid Day, told IFLScience.
Tomorrow, more than 200 events will take place around the world in more than 60 countries to highlight what can be done about asteroids. You can check these all out on the Asteroid Day website, and there will also be more than 20 live streams for you to tune in to (in addition to a Q&A on Reddit). Some notable speakers and backers include Queen guitarist (and astrophysicist) Dr Brian May and former Canadian astronaut Chris Hadfield.
Above, the first in a series of videos discussing Asteroid Day, narrated by Neil deGrasse Tyson.
Perhaps the most important thing that needs to be done is to improve how we track asteroids. We know of thousands of so-called near-Earth objects (NEOs), but it’s estimated that more than three-quarters remain undetected.
There are numerous efforts to track asteroids, such as NASA’s Planetary Defense Coordination Office (PDCO). But some, including Richters, think we aren’t doing enough. For example, in February 2013, the Chelyabinsk meteor passed through the atmosphere undetected, exploding over Russia and injuring hundreds.
Indeed, Asteroid Day itself takes place on the anniversary of the largest recorded impact in recent history – the Tunguska event in Siberia on June 30, 1908, which flattened 2,000 square kilometers (770 square miles) of forest and could have caused untold damage if it had struck a city.
Currently, there are no asteroids we know of on a collision course with Earth (you can see the biggest threats at this NASA website). But we need to have several decades of warning just in case we do find one, in order to properly deflect it.
"We're not currently aware of something that will strike any time soon, but it's better to be prepared when the situation arises," said Richters.
The goal of Asteroid Day is to ensure we are prepared for a repeat occurrence of the Tunguska event. But what could be done if we found an asteroid on a collision course with Earth? Well, there are a number of proposals in the pipeline. These mostly involve techniques to subtly change the trajectory of an asteroid decades before it hits us, changing it just enough so it misses.
One such proposal is a “gravity tractor”, which would involve keeping a large spacecraft in one position above an asteroid and using the small gravity of the spacecraft to slowly pull the asteroid off course. Another method would involve slamming an impactor into an asteroid, again changing its trajectory. NASA and ESA will be testing out such a method with their Asteroid Impact and Deflection Mission in 2022.
NASA and ESA's Asteroid Impact and Deflection Mission will demonstrate how we could save our planet. ESA - ScienceOffice.org
If Armageddon is more your thing, though, some have suggested we could use a nuclear weapon instead. This wouldn’t involve blowing up an asteroid but, rather, we’d explode a bomb near the asteroid, dramatically altering its trajectory rather than gradually over time. Of course, safety issues regarding launching nuclear weapons into space means this hasn’t had much serious discussion yet.
But, clearly, there is more we could be doing to prepare for such an eventuality. In a world threatened by climate change and other natural disasters, asteroids represent a threat that could be just as catastrophic, but which receives little public attention.
"Asteroid Day itself isn't going to save the planet," said Richters. "It's the scientists, the men and women working day and night in the field, that we are here to support. The asteroid issue is not like black holes or dark matter, it's not one of the top sciences. There's a huge way to go, so just increasing their respectability is something I'm striving for."