As my colleague Jesse Walker blogged earlier today, a meteor exploded over the Ural region of Russia causing some damage and a lot of alarm. is reporting that the meteor most likely massed about 40 tons 7,700 tons*, making it the biggest object recorded to hit the Earth since the Tunguska strike in Siberia back in 1908. further reports:

A meteor that exploded over Russia this morning was the largest recorded object to strike the Earth in more than a century, scientists say. Infrasound data collected by a network designed to watch for nuclear weapons testing suggests that today's blast released hundreds of kilotonnes of energy. That would make it far more powerful than the nuclear weapon tested by North Korea just days ago and the largest rock crashing on the planet since a meteor broke up over Siberia's Tunguska river in 1908.

In about three hours, a much bigger near earth object, asteroid 2012 DA14 will fly past the earth at about 17,000 miles away. This asteroid is nearly 150 feet across and its estimated mass is about 130,000 metric tons. If it were to hit the earth it would release the energy equivalent of 2.3 megatons of TNT, or nearly 150 times the explosive power of the atomic bomb dropped on Hiroshima.

In my 2005 column, "Earth Killers from Outer Space," I asked if a planetary defense agency might be a government program that you can support? I also noted:

Defending against NEOs is a classic example of a public goods problem. A public good is one, such as national defense, with low costs for an extra individual to enjoy, and high costs to exclude anyone from enjoying. This means that it's unlikely that any particular individual (namely you or me) would pay out of his own pocket to see that the good is provided.

In such situations, we turn not to markets, which excel at providing private goods, but to mechanisms of collective action, generally the government. Naturally, any new Planetary Defense Agency will suffer all the problems that afflict government bureaucracies, especially the innate drive to seek more money and power by exaggerating risks. But given the devastating consequences of an Earth Killer strike, it makes sense to take some strong collective action to protect ourselves and future generations against this risk.

Well, what do you think?

*updated over at - Hat tip Eric Hanneken.