Using the same logic if an alien came to earth to study us it will not disclose being an alien for obvious reasons so in theory if you take the probability that there is inteliigent life out there and some of it may be more ancient than us we could have aliens here already studying us.
There was a news report on the bbc site about inconsistent flickering from a star maybe the same as this and someone theorised a large number of comets but it could also be planetary collisions. There may be star systems with an absolute huge number of planets compared to ours and planetary collisions are common.
Our technology while amazing to us is still pretty primitive. In a 1000 years from now someone may discover that there are particles that travel far faster than light and are used for communication across the universe. They will realise the universe is full of communication already.
