KABOOM !

If there's a 170 kilotonne explosion in the atmosphere and no-one hears it, does it make a sound ?

A huge fireball exploded in the Earth's atmosphere in December, according to NASA. The blast was the second largest of its kind in 30 years, and the biggest since the fireball over Chelyabinsk in Russia six years ago. But it went largely unnoticed until now because it blew up over the Bering Sea, off Russia's Kamchatka Peninsula.

The space rock exploded with 10 times the energy released by the Hiroshima atomic bomb. Lindley Johnson, planetary defence officer at Nasa, told BBC News a fireball this big is only expected about two or three times every 100 years. Measuring several metres in size, the space rock exploded 25.6km above the Earth's surface, with an impact energy of 173 kilotons.

It's reassuring that most of our planet is still empty and that asteroids with such enormous energies don't make it to the ground. Less reassuring is that an explosion many times more powerful than the atomic blast that destroyed Hiroshima can occur without anyone even noticing very much and that it was completely unexpected. Even less reassuring than that is that no-one seems particularly alarmed by this. I mean, it's nice to avoid a panic, but could we maybe just please be a little bit more panicy than we are ?

On the other hand, maybe not. Maybe everyone is already at Peak Panic because of other issues and they don't have any panic left to give. Perhaps the political situation is so dire that people are hoping for another solution entirely. If so, the asteroid can help them with that soon enough.

US detects huge meteor explosion

A huge fireball exploded in the Earth's atmosphere in December, according to Nasa. The blast was the second largest of its kind in 30 years, and the biggest since the fireball over Chelyabinsk in Russia six years ago. But it went largely unnoticed until now because it blew up over the Bering Sea, off Russia's Kamchatka Peninsula.