The most important question, if they're alien, are they coming or going?. It's too long of a trip for a visit.
Consider that the technologies to build spacecraft were largely in development during the 1930's but got paused by war. Once the war was over those resources went to developing spacecraft to prevent the next war. Some key points to follow:
-Funding for high performance aircraft and spaceflight suddenly existed after 1945.
-It continued to increase due to the cold war.
-It continues to increase due to telecommunications.
Add to the fact that access to video cameras has also increased continuously. One would think the increase would be exponential with the advent of camera phones but I believe the quality of cameras is causing a negative feedback which is why the increase stays linear.
Funny story, I may be closely related to the Bill Uhouse that broke the J-Rod story.