My goodness, what complete nonsense. Please stop encouraging gullible people to believe in aliens hiding behind the moon, or ghosts, or angels and demons, or Bigfoot, or the Loch Ness monster, etc.

As soon as you tell me where there is an advanced civilization on another planet, and then credibly explain how they would possibly get to Earth from their planet, then I will start paying attention. People that believe in these things have no concept of the distances involved, the times involved and the resources involved. Imagine all of the energy that humanity currently uses across the planet (oil, coal, gas, nuclear, solar, wind, etc) in one year. Now take 400 years of that amount of energy. Now you would have approximately the amount of energy you will need to send a decent sized space ship to a planet in the closest spriral galaxy (Andromeda). Of course, going at 10% light speed (something humans have only dreamed of in science fiction), it will take 20 million earth years more or less just to go one way. Don't start going down rabbit holes to talk about warp drives and worm holes, etc. These are for the also science fiction until scientists can prove otherwise.

Humans have been, are and always will be alone on planet earth --- sorry no aliens are coming for a visit. Earth was formed 4.5 Billion years ago, We sent up our first little satellite only about 65 years ago, and our civilizations my be gone in a short time if we don't start focusing on what is really important.