A video has outlined the top five methods that can save Earth from getting hit by a city or even a planet-killer asteroid. It also shows what space agencies and governments can do if they were not able to detect a killer asteroid on time.

The main idea behind preventing an impact is all about affecting the movement of an approaching asteroid. This can be done by either pushing the asteroid off its trajectory or slowing it down so it would pass before or after Earth as the planet travels around the Sun.

A video shared via YouTube by PBS Space Time identifies the various solutions space agencies and governments can use to successfully deflect an asteroid. The first one involves launching a spacecraft and intentionally crashing it into an asteroid. Theoretically, this would nudge the asteroid away from its current trajectory.

The second solution involves launching a nuclear missile. But instead of directly hitting the asteroid, the device will be detonated next to the space rock in order to push it off course.

The video also noted that space agencies can also send a spacecraft to paint one side of the asteroid white. As the light from the Sun hits the newly-painted and highly-reflective side of the asteroid, the heat generated by sunlight will push the asteroid away, causing it to miss Earth entirely.

Space agencies also have the option to use the concept of a gravitation tractor to deflect an asteroid. This can be achieved by launching a massive spacecraft and flying it alongside an asteroid for about a decade. The mutual gravitational attraction between the spacecraft and the asteroid will allow the former to pull the latter away from a collision course with Earth.

As PBS Space Time noted, these solutions will only work as long as the approaching asteroid is detected way before it hits Earth. But, if Earth only has a month or so to prevent an impact event, the only way this can be achieved is by completely blowing up the asteroid.

This can be done by launching a thermonuclear device equipped with a high-speed kinetic impactor tip. According to the video, the impactor tip would create a large crater on the asteroid where the device could detonate it. The resulting explosion would send shockwaves across the asteroid, causing it to break up into pieces that are small enough to burn up in Earth’s atmosphere.

Pictured; an artistic illustration of an asteroid flying by Earth. NASA