alien invasion of Earth

The Earth is our home. It is the only planet humans are aware of capable of supporting us. We have no alternative. If a hostile alien race finds us we must defend Earth. We currently have no plan for planetary defense. Radio and television signals have announced our location to every star within about 80 light years. What happens out there, matters. Do you know the date of the alien invasion of Earth? Can you run in the shoes you are wearing?