NASA: Our planet is a clay pigeon

The Earth is at the mercy of asteroids and comets, and in the event that a large celestial body collides, there would be almost no time to prevent or at least mitigate the disaster, according to NASA.

"We are completely unprepared for a sudden asteroid or comet impact," warned Joseph Nuth, who works at the Goddard Space Flight Center, at the American Geophysical Union conference in San Francisco.

He explains that large comets or asteroids that could wipe out civilization from Earth are very rare, but can collide with our planet every 50 to 60 million years.

"Since the comet that caused the extinction of the dinosaurs hit 65 million years ago, we may have broken that deadline a little bit," says Nuth.

He warns that the biggest problem is that there is nothing we can do to prevent it at the moment.

Comets usually pass at a greater distance from the Earth, but occasionally, however, they are found in its vicinity, according to the Guardian.

The last close encounters occurred in 1996, when a large comet hit Jupiter, and in 2014, when it passed close to Mars.

Since that comet had only been discovered 22 months earlier, and had there been talk of a potential collision with Earth, we would not have had enough time to launch a mission to deflect the trajectory.

"Preparation for the launch of a spacecraft takes five years, and we only had 22 months," explains Nuth.

At the beginning of this year, NASA established the Department of Planetary Defense, which deals with the detection and monitoring of space objects that are near the Earth.

Scientists have discovered that 90 percent of space objects near Earth are larger than a kilometer, that is, they are large enough to devastate the planet.

Smaller space bodies can also be quite dangerous. Out of a total of 1.748 potentially dangerous asteroids, NASA found 874 asteroids with a size of one kilometer.

Los Alamos National Laboratory scientist Cathy Plesko says there are two ways to defend against an asteroid - a nuclear warhead or a kinetic impactor, which is basically a big cannon.

"The cannon technology is very good, because it intercepts the target at high speed and is more effective than explosives," she explains.

However, calibrating the cannon would take much longer than using nuclear weapons to defend the planet.

"The problem is that we don't have enough information about what is in a possible asteroid or comet," explains Plesko.