What do you think they would do? Charge at you holding laser pistols in their tentacles? Why would they invade us? For the resources? The rest of our solar system holds thousands of times the amount of any concievable resource than Earth has. The only thing Earth has more of then any other planet of our solar system is biomass, and odds are that our biomass would be completely unusable to any aliens because of biological incompatibility. So, if they wanted to take our solar system, they would probably just bomb our entire planet into oblivion with relativistic projectiles before we even knew they were there, kinda like you might exterminate a termite infestation in a home you just moved into.