When a gravitational source exerts force on an object, the varying distances of points on the object from the source cause differences in gravitational strength, resulting in a tearing effect. This difference in gravitational force is known as tidal force.
Expanding this concept to the universe, tidal force is omnipresent.
When an object's mass is large enough, it becomes a gravitational source.
In space, whether it is the radiant Sun or Blue Planet itself, or the Moon orbiting Blue Planet, and the many planets within the Solar System, all belong to gravitational sources.
However, under normal circumstances, tidal forces cannot tear an object apart. The simplest example is Blue Planet itself.
Blue Planet is influenced by the dual gravitational sources of the Moon and the Sun, and the tidal phenomena on Blue Planet are manifestations of tidal force, yet Blue Planet itself has not been torn apart by the gravity of the Sun and the Moon.
But the meteorite that is about to collide with Blue Planet is different this time.
First of all, its size is neither too large nor too small. Once it entered the Earth-Moon system, it was influenced by the triple gravitation of the Moon, Blue Planet, and the Sun.
Originally, according to the strength of the meteorite itself, it would not have been torn apart by the gravity of Blue Planet, but since it threatened the safety of Blue Planet, it was mined with holes and then exploded at the center.
The nuclear bomb detonated by the Federation on the meteorite did split the meteorite into two pieces, but it also destroyed the meteorite's original internal structure.
Simply put, the nuclear bomb detonated by the Federation not only blasted the meteorite apart but also caused fractures in the two separated parts.
If it was just left alone, there would be no problem, but as the meteorite's trajectory gradually approached Blue Planet and it experienced increasing gravitational influence from Blue Planet or was outright captured by Blue Planet's gravity, the problem emerged.
It's like a bedsheet, where three people couldn't tear it apart when it's intact. But once a big hole is poked in the middle and torn into two parts, the remaining part, when pulled by three people along the fracture, can easily be torn apart.
So with the same principle, the already cracked meteorite, under the dual gravitational influence of Blue Planet and the Moon and with the added gravitational influence of the Sun, was torn into three parts under threefold gravitational force.
The meteorite being torn into three parts is not the issue, as long as they continue to follow the previous trajectory, it would just mean three meteorites grazing Blue Planet.
But the problem is that when the meteorite fractured, it simultaneously lost weight, which meant that all three meteorite pieces were captured by Blue Planet's gravity and headed towards Blue Planet.
On the cosmic scale, this matter is minuscule; it's just a few meteorites, insignificant whether to the Moon or Blue Planet.
In fact, Blue Planet experiences the impact of tens to hundreds of tons of meteorites falling every day, but most fall in uninhabited areas or burn up in the atmosphere before reaching the ground, with very few actually hitting the surface and causing an impact.
So from a cosmic perspective, meteorite impacts really aren't significant.
But from another perspective, meteorite impacts can be deadly.
Fortunately for modern human civilization, technology has advanced to a certain level, allowing humanity to begin venturing beyond its home planet, and possessing some capabilities to withstand and defend against such disasters, it can preserve a spark of human civilization to some extent in the face of catastrophe.
But what if a meteorite impact occurred in times when human technology wasn't as developed?
No need to go too far back, just two hundred years ago in the 18th century, if a meteorite impact of this scale occurred, human civilization could meet the same fate as the dinosaurs, hands off the keyboard, it's game over.
Because with the technological level of the steam era two hundred years ago, humanity would be powerless against such a disaster, unable even to dig shelters for refuge.
Yet even with modern human civilization gradually gaining strength to deal with such disasters, our capability remains limited.
The rescue plan assembled with nearly all resources on Blue Planet was nearly halfway successful, but now the meteorite, which was supposed to be pushed away from its impact trajectory, not only got pulled back by Blue Planet's gravity but also split into three parts, causing the leaders of all countries aware of this to instantly have their blood pressure spike and heart rate jump to 120.
We still haven't dealt with one four-kilometer piece, and now there are three more five-kilometer pieces. All prior efforts have been wasted, and the crisis humanity faces hasn't eased one bit, but has worsened instead.
In light of this situation, leaders from all nations feel like cursing, "This is a rip-off!"
But as four meteorites are heading towards Blue Planet, they can't give up on stopping them and wait until the meteorites fall to flip the bird, so even though they want to quit, the leaders convened an emergency meeting to discuss how to address the current crisis.
"Currently, four meteorites are approaching Blue Planet at a speed of 11.5KM/S, and without accident, they will impact Blue Planet in a few hours," a scientist from the United Nations action group is reporting to the assembled leaders, besides reporting the time of the meteorite impact, he also provided the impact locations: "Based on orbital calculations, the impact sites are likely to be North America and the Pacific Ocean."
The scientist didn't mention the disasters triggered by the impact because everyone knows if all four meteorites hit, there's no point in considering the future; humans would, like the dinosaurs, face a great extinction risk.
Thus, the priority is to find a way to stop these four meteorites to avoid them hitting Blue Planet.
At least, prevent all of them from falling.
"What means do we have now to intercept those meteorites?" In this crisis, it's the leaders of the top five Blue Planet powerhouses who first inquired, capable of thinking about interception measures at such a time.
"Honestly, we don't have any feasible solutions left. In these few hours, even if we wanted to launch spacecraft for interception missions, we don't have enough time, not even the time to refuel them, nor do we have ready spacecraft," the leader of Britain expressed with a heavy heart, his face filled with despair.
As an island nation, Britain neither has the sufficient strategic depth nor resources; its capabilities to deal with such a world-scale disaster are seriously limited.
However, at this point, the leader of Lucia had a different opinion. He declared firmly and powerfully, "We still have the final measures! Our Lucia spacecraft is still in space, and with them are over twenty nuclear bombs we launched! These nuclear bombs are enough to shatter these meteorites!"
The words of Lucia's leader made everyone's eyes brighten, as it's indeed their last measure and also the only piece of good news under the current circumstances.