An expert warned that Earth would have little time to react if a space rock from the asteroid belt gets dislodged from its orbit and heads toward Earth. If the asteroid is big enough, it could cause an impact event that could trigger mass extinctions on the planet.

The asteroid belt, also known as the main belt, lies in between the orbits of Mars and Jupiter and contains various irregularly shaped space rocks. Unlike near-Earth objects, which are known to approach Earth from close distances, those in the asteroid belt usually remain within their orbits.

However, according to Carl Ejnar Nielsen of the University of Copenhagen, it is possible that an asteroid would get dislodged from its main belt orbit. This can be caused by a variety of factors such as a collision with another asteroid. It is also possible that the gravitational pull of Mars or Jupiter could change the asteroid’s trajectory.

If this happens, Nielsen noted that the asteroid could end up on a collision course with Earth.

“Some may still sneak in on us. If an asteroid is deflected from its orbit in the asteroid belt to hit Earth half an orbit later, we have precious little time to act,” he said according to Express.

According to Nielsen, a rogue asteroid from the main belt could catch Earth by surprise depending on the direction it’s traveling. If it approaches from behind the Sun, Earth may not be able to detect the asteroid until it’s too late.

“We may also miss an interstellar interloper, as its trajectory can be obscured by the Sun while on its inbound leg towards the Sun, after which it will present its dark side to us while outbound, maybe to hit with no warning in the middle of the day,” Nielsen explained.

As noted by other scientists, the main belt, as well as other regions in space, may hide mountain-sized asteroids. If these massive space rocks find their way towards Earth, the resulting impact event could trigger a series of catastrophic effects that could eventually wipe out more than half of life on the planet.