Alien invasion? I'll ask them to mine some bitcoin with their amazing technologies!
How do you know they have amazing technologies?
We might be much smarter than them...
You need more than Amazing technologies to travel lightyears in space. The fact that there is no other civilization in Solar system they must came from other solar system. Most likely they came from more than 22 light years from Earth. Because Alpha Centauri System most possibly can't support life.
Do you know how take it takes to make interstellar travel. The civilization technology must be Level II type while today we are still not a Level I civilization. They will be superior in almost every aspects to us. They have to the ability to control weather like rain, drought, hurricane, global warming, cause or prevent earthquakes, they can terraform a planet. There is a big possibility they achieve singularity with the machines. They are near immortal.
How we defeat that kind of enemy. Our only choice is to hide underground and wait for the right moment and learn their technology and find their weakness then defeat them.