Last week, a giant rock, over a mile wide, passed close to Earth. NasaThe National Aeronautics and Space Administration, responsible for the US space programme. described the object, which flew 10 times faster than a bullet, as "potentially hazardousRisky, dangerous. A hazard is something that gets in your way, that might trip you up or hurt you.". In the words of Times writer Katie Gibbons: "it flouted galactic social distancing guidelines".

Luckily for us, a "close shave" in astronomical terms means 3.9 million miles away - more than 16 times the distance between us and the Moon.

And Paul Chodas, the manager of Nasa's Centre for Near-Earth Object Studies, has reassuringly said, "There are no asteroids which have any significant chance of hitting the Earth that are of any significant size."

Indeed, Nasa scientists believe they know in advance about 90% of the near-Earth asteroids big enough to cause serious problems for humanity.

But that still gives room for some to go unnoticed.

On Monday, another space rock, which no one had tracked, flew just 4,000 miles above the Pacific Ocean. Fortunately, it was only the size of a truck.

But what would happen if a larger object slipped past the telescopes?

Anything a mile or so across, hitting the Earth at speeds of up to 30,000 miles per hour, would cause incomparable damage.

The dust coughed up from the ground would black out the Sun. Very little life would survive. We would probably become like the dinosaurs: extinct.

To protect Earth from such an event, scientists have come up with a few truly ingenious plans.

Some scientists say we could spray-paint an approaching asteroid white, so that the Sun reflects off one side more than the other, slowly diverting it off-course.

Others suggest we could fly a spaceship alongside it, using the laws of gravity to take it slightly off course.

If it is too close to try anything subtle, we could just fly a spaceship into it or, better still, attack it with an nuclear missile. This would splinter it into fragments. Being hit by lots of smaller rocks is better than being struck by one big one.

Yes. Though unlikely, an asteroid could destroy human civilisation overnight. In 2019, Nasa's Office of Planetary Defence admitted that an unseen asteroid suddenly coming straight for Earth is still a real threat. This is why many organisations are committed to developing strategies to protect our planet. Something being unlikely doesn't mean we should ignore its possibility.

No. There is a vanishingly small probability that a civilisation-ending space rock will hit our planet. We should focus on other, more likely, disasters. Preparing ourselves for the next pandemic could be one idea. Reducing carbon emissions is another. We could also discard the huge arsenal of apocalyptic nuclear warheads dotted across the world - except for those we would shoot at an asteroid of course.