Above our heads at night are millions of stars with millions of planets that scientists now say stand a good chance of containing life. There may even be intelligent life.
But the important question is: has it paid us a visit?
It's a subject that will be reviewed in depth at the Devils Town UFO Rendezvous. That location was chosen because of a movie called Close Encounters of the Third Kind which was filmed there 41 years ago.
The storyline is that an alien civilization chose to make contact with the human race at this formation in the northwestern Black Hills.
That's fiction of course. But people have been seeing strange sights in the sky for a very long time. And some UFO investigators such as David Marler think there is compelling evidence that they are real.
"And it goes beyond just eyewitness testimony. Many of these cases including military cases, involve radar and I mean multiple radar; ground-based radar, airborne radar, airborne visual sightings, ground-based visual sightings," Author and UFO Investigator David Marler said.
Several astronauts have also reported airborne objects they couldn't identify.
"When you have much corroborative testimony, you have to look at this in a serious light and try to figure out what we're dealing with," Marler said.
While we still don't have material evidence, we do have thousands of pictures. Some of which are just a hoax.
Digital photography has made the task of judging UFO photos much more complicated. Astronomer Marc D'Antonio, says it's difficult but it can be done.
"You actually could see the artifacts created by the process of rendering. And you could see that in the shadows," Astronomer and Photoanalyst Marc D'Antonio said.
D'Antonio says most photos of UFOs are either faked, or of ordinary objects such as birds, balloons, or drones.
All of these mysteries will be discussed at the UFO rendezvous in the coming days. It may be one of the most compelling mysteries of our time, the question of what are those strange things some of us are seeing in the skies?
The Devil's Tower UFO Rendezvous begins Thursday at 10 a.m. at the Best Western Hotel in Hulett, WY and runs through Saturday.