Is there life on other planets? This question fascinates everyone from adults and children to scientists and philosophers. Some of the most popular movies of all time — from Close Encounters of the Third Kind to E.T.: The Extra-Terrestrial — have sparked our imaginations and kept us wondering about what — or who — else might be out there!

Of course, some people firmly believe that aliens do exist. Many of these people are more fascinated with the questions of whether aliens visit Earth and, if they do, how they get here.

Would they pilot flying saucers, or would their spacecraft be similar to what Earth's astronauts use? Or would advanced alien spacecraft look like something we’ve never seen before? Would we even be able to SEE alien spacecraft?

Think about it for a minute. If aliens exist and could travel here, they would obviously have advanced technology. Do you think the same rules of science apply where they come from? Would two plus two equal four in outer space? Wouldn’t it be interesting to find out?

Many people believe that they have spotted alien spacecraft from time to time. From unexplained lights in the sky to mysterious objects floating on the horizon, there have been many claims of alien sightings.

The official term for what people see during such alleged sightings is an unidentified flying object or UFO. Originally used by the military, this term refers to an unusual object in the sky that can’t be immediately identified by an observer as a known object.

Technically, the term UFO refers to any unidentified object in the sky. In our modern culture, though, the term UFO is used mainly to refer to supposed sightings of alien spacecraft.

Alleged UFO sightings are not a purely modern phenomenon. Experts note that sightings of “mystery airships” have occurred since the late 1800s. Interest in UFOs increased greatly during World War II, when American fighter pilots used the term “foo fighters” to refer to unexplained sights in the sky.

In June 1947, private pilot Kenneth Arnold reported seeing several “flying saucers” or “flying discs.” Around the same time, the United States military recovered debris from a highly-classified experimental high-altitude surveillance balloon that crashed near Roswell, New Mexico. Despite the military’s explanations, many people believed the “Roswell UFO incident” involved the crash-landing of an alien spacecraft.

These events led to increased interest in UFOs and whether alien life forms might visit Earth. Although some research has been done from time to time by military organizations, there has been little scientific study of UFOs. Most UFO research is conducted by private groups of individuals with an interest in the topic.

Although a very small percentage of UFO sightings remain unexplained, most UFO sightings are eventually identified and explained. Many supposed UFO sightings are later determined to be sightings of conventional objects, such as aircraft, missiles, kites, or weather balloons.

Many other supposed UFO sightings are eventually determined to be caused by natural phenomena, including reflective or oddly-shaped clouds and astronomical objects like meteors or planets.

Of course, some UFO sightings are complete hoaxes. Given the amount of public interest in aliens, some people just can’t resist pulling a fast one to stir up UFO enthusiasts.

So what’s the bottom line? Despite what UFO and alien enthusiasts might believe, the U.S. government’s official position is that there is “no evidence that any life exists outside our planet, or that an extraterrestrial presence has contacted or engaged any member of the human race.”

Did you get it?

Test your knowledge

Wonder What's Next?

Join us in Wonderopolis tomorrow as we search for the world’s tallest mountain!