Outside experts have raised doubts about whether a loud boom and a gaping crater found in Nicaragua last weekend were caused by a meteorite, as the government has claimed.

The threat of space rocks smashing into Earth is bigger than previously thought, say scientists studying the terrifying meteor that exploded without warning over a Russian city last winter.

NASA is charged with spotting most of the asteroids that pose a threat to Earth, but doesn’t have the money to complete the job.

A blue-ribbon panel of scientists is trying to determine the best way to detect and ward off any wandering space rocks that might be on a collision course with Earth.