2. It is also possible to install a large thrust rocket on a small celestial body, even better if it is a nuclear rocket. This method is more accurate, easier to control and has a high success rate than nuclear bomb explosion. But installing a rocket will be much more difficult than a nuclear explosion.
3. High-power laser can make the material on the surface of small celestial bodies evaporate and eject, forming a recoil force and gradually changing the orbit of small celestial bodies. However, the laser directly shooting Xiaotian's physical quality from the earth is basically zero. Because the distance is too far, the energy of the laser is scattered too much, which is difficult to control accurately. Therefore, it is necessary to emit laser near small celestial bodies. Illuminate nearby small celestial bodies.
But there is a simpler option, using optical methods. That is to use a large condenser to reflect sunlight and illuminate the surface of small celestial bodies. A condenser with a diameter of several hundred meters is much simpler and more powerful than a super laser, and does not need huge energy supply.
5. As for particle weapons. In fact, it is useless, because it is more difficult to manufacture than super laser and the effect is much worse.
I think the fourth is better, but the probability of an asteroid hitting the earth is very small, because the earth is very small.