What happens if the moon disappears? Or if some planets in the solar system collide and get into space. Will it affect the earth?
If the Moon disappears (though we don’t know how it could happen) the sky would be darker at night, but otherwise we probably wouldn’t notice it as much. After a long time, perhaps the earth’s magnetic field would weaken.
The planets are in very different orbits far apart, there is no risk that we will see them collide for billions of years. What would happen then depends on exactly what happens. If the earth were to collide with another planet, it would certainly be impossible to live here, but you need not worry about something like that.
It is much more dangerous in traffic and it is important that you be careful there.