CONSIDER IT A WARNING: Asteroid blast reveals holes in Earth’s defences. “As the US government ponders a strategy to deal with threatening asteroids, a dramatic explosion over Indonesia has underscored how blind we still are to hurtling space rocks. On 8 October an asteroid detonated high in the atmosphere above South Sulawesi, Indonesia, releasing about as much energy as 50,000 tons of TNT, according to a NASA estimate released on Friday. That’s about three times more powerful than the atomic bomb that levelled Hiroshima, making it one of the largest asteroid explosions ever observed.”