UFOs?

But, some would say, we already have evidence of travel between the stars. It is documented every day in the checkout lane at the supermarket, where flying saucers and alien abductions are standard fare in the sleazy tabloids one must get past just to buy milk! For example, you can see with your own eyes two flying saucers over London in the adjacent figure. (This photograph was manufactured on a home computer using readily available programs as a demonstration of how easy it is to produce "authentic" UFO photographs.)
Extraordinary Claims Require Extraordinary Evidence
But extraordinary claims require extraordinary evidence, and when claims of alien spacecraft and alien abductions are put to the scientific test, they fail. Nothing would be more exciting than for one of these claims to be true, but alas most are hoaxes, most of the rest are honest observational mistakes, and the few that do not fit either category may be genuine mysteries but usually have simpler possible explanations than alien spacecraft. And those who believe that "the government" is deliberately suppressing evidence clearly credit the government with far more efficiency than is warranted!
The Planet Venus
Investigators who have looked objectively at the UFO evidence have found that many UFO sightings that are not deliberate hoaxes are just the planet Venus, for example. That so many well-meaning people could mistake a distant planet for a spacecraft should give us pause when we hear the next outrageous claim regarding alien spacecraft.