How UFOs Work

UFO sightings have been associated with so-called alien abductions, in which people say that they have been transported to an alien spacecraft and subjected to a variety of physical examinations -- even alien cross-breeding experiments.

UFOs have also been linked to crop circles, strange and sometimes unexplained patterns that form overnight in fields.

UFOs have been blamed for animal mutilations -- horses, goats, cows, deer and other creatures found drained of blood and with their organs removed. The alien theory arises because typically no tracks are found around the animal to indicate that a human was responsible.

During a UFO sighting, strange phenomena are often reported, such as radio and TV interference or car-ignition failure. Many UFOs leave strange calling cards, such as indentations in the ground; burned or flattened vegetation; spider-web-like strings that hang from telephone poles and trees and disintegrate at the touch; and chunks of unidentifiable debris.

So, are they really alien spacecraft piloted by extraterrestrial beings, or are they terrestrial objects that just haven't been properly identified? The question has raised a good bit of controversy, pitting those who believe in UFOs against those who say they need to see more scientific UFO evidence.

Surveys show that the overwhelming majority of Americans believe that intelligent life exists elsewhere in the universe. More than 60 percent of respondents to a 1997 CNN poll said they believe aliens have contacted humans; approximately 50 percent said they think aliens have abducted humans; and 80 percent believe the government is hiding something about alien contact.

People who claim to have seen UFOs are confident that what they've seen is real. They say these alien beings have come to Earth to study the human race, create a new hybrid species or simply to communicate with humans.

But skeptics say there is a startling lack of real scientific evidence to prove -- or disprove -- the UFO phenomenon. They argue that the majority of UFOs turn out to be identifiable phenomena -- everything from weather balloons to meteor showers to hoaxes.

Back in the 1940s, the United States government was heavily into UFO research. The U.S. Air Force began investigating UFOs in 1948 under a program called Project Sign. The name was later changed to Project Blue Book, and between 1948 and 1969, the government investigated more than 12,000 UFO sightings. Of these, 11,917 were discovered to be terrestrial objects such as weather balloons and satellites; weather phenomena such as lightning and reflections; astronomical occurrences; or hoaxes. The remaining 701 cases were unexplained.

In 1969, the Air Force shut down Project Blue Book, citing a lack of conclusive evidence. Project Blue Book concluded that:

UFO research continues in the private sector. The SETI (Search for Extraterrestrial Intelligence) Institute regularly monitors the skies, searching for signals from faraway planets. In the late 1990s, they picked up on something -- a repeated pattern coming from about 1 million miles away. But within a few hours, SETI scientists had identified the pattern as a signal from a sun-watching observatory called SOHO, which is in orbit about 1 million miles from Earth. (To learn more about SETI, its projects and how you can be a part of the search, see How SETI Works.)

Although Project Blue Book ended the official government investigation into UFOs, there are those who believe the government is hiding something.

On a summer evening in 1947, residents just outside of Roswell, N.M., saw strange lights in the sky and then heard a loud crash. In the morning after a rash of severe thunderstorms, a ranch foreman named Mac Brazel was out checking his sheep when he found strange debris. He contacted his local sheriff, who notified the government. The debris was taken to Roswell Army Air Field and eventually flown to Wright Field in Dayton, Ohio. On July 8, 1947, Colonel William Blanchard of the 509th Bomb Group in Roswell issued a press release stating that the military had recovered the wreckage of a "crashed disc." A few hours later, General Roger Ramey, Commander of the Eighth Air Force at Fort Worth Army Air Field in Texas, issued a second press release repudiating the first. According to Ramey, the debris Blanchard's men had recovered was nothing more than a weather balloon and its radar detector.

Which press release was true? UFO believers say the first one was true, and the second was part of an elaborate cover-up that has stretched on for more than a half-century.

They believe that the government actually recovered a craft and its alien crew. Eyewitnesses report having seen covered bodies being carried away by the military. A few people said they were present at an alien autopsy. Roswell theorists say the government has been secretly meeting with aliens since the crash at a place called Area 51 in a remote part of Nevada.

Another theory relating to the government's supposed cover-up involves the silencing of witnesses. A number of UFO witnesses report having been visited by men in black suits who tried to intimidate them into silence. These so-called "Men in Black," who came to the public's attention in Gray Barker's 1956 book, "They Knew Too Much about Flying Saucers," are thought to be either aliens hiding their own evidence or government agents trying to cover up alien landings. According to most sources, Barker's book is a work of fiction. The mythology surrounding the Men in Black has spawned two popular movies, a TV series and a video game.

While the government denies any involvement in UFO cover-ups, another group of people claim very intimate involvement with UFOs: alien abductees.

Have aliens really taken people into their spacecraft and experimented on them? Many say they have. Probably the first account of an alien abduction came from a New Hampshire couple named Barney and Betty Hill. On September 19, 1961, the couple was driving through a rural area in central New Hampshire when they noticed a moving light in the sky. As the object came closer, they saw that it was large and flat with multicolored lights and many rows of windows. When Barney looked at the craft through his binoculars, he reportedly saw creatures inside it, one of which appeared to be the leader. Frightened, the couple drove home. Several days after their sighting, Betty began to have nightmares about being inside the craft. Later, under hypnosis, the couple recalled having been taken into the UFO and experimented upon.

Were the Hills, and the thousands of other people who say they have been abducted since then, telling the truth? Skeptics claim the aliens with wraparound eyes that Barney described aired on an episode of "Outer Limits" just 12 days before the hypnosis session in which he described them.

But the stories of abductees are remarkably similar. Many people recall being bathed in light and feeling paralyzed. Then there is a feeling of being carried in a beam of light to a waiting alien spacecraft. They describe an examination room in which their bodies are poked, prodded and studied in various ways. Many tell of having sperm or eggs removed from their bodies and used to produce alien-human offspring, which some people claim to have met when they returned to the spacecraft at a later date.

These memories may sound like the stuff of imagination, but some researchers say alien abductees share many of the same post-traumatic stress disorder symptoms as war veterans. When they listen to audio tapes of sounds that mirror their experiences, they exhibit physical symptoms -- their palms sweat, their muscles contract and their heart rate increases, Harvard University researcher Richard McNally and his colleagues reported in the July 2004 issue of the journal Psychological Science.

Also, the timing of the abduction stories appears to coincide with the sighting of UFOs nearby. Many of the abductees are reported as missing when they claim to have been abducted, and when they return, they have strange cuts and bruises on their bodies.

Although UFO sightings have become more common in the last half-century, there have been sightings of strange flying objects recorded throughout the ages. Author Erich Von Däniken has written more than two dozen books, including "Chariots of the Gods? - Unsolved Mysteries of the Past," claiming that aliens have been visiting Earth for tens of thousands of years. The Bible, he says, is filled with references to alien visitors. He contends that they helped build the pyramids, introduced art and social order to ancient humans and even interbred with our ancestors to create our modern species.

Ancient Indian Sanskrit texts purportedly describe flying machines, called vimanas, used by the gods to fight battles in the sky. In one text, vimana construction is described (in translation):

Probably the first modern close encounter with alien spacecraft occurred on June 24, 1947. A private pilot named Kenneth Arnold was flying near Mt. Rainier in Washington state when he spotted nine, crescent-shaped flying objects. He observed the objects to be moving at well over 1,000 miles per hour, far faster than any man-made aircraft could fly at the time. One reporter writing up the event referred to the objects as "flying saucers," and the description stuck.

Since then, there have been reports of UFO sightings in England, Australia, China, Mexico, Russia, Spain, Italy, the United States and most other countries throughout the world.

To find out more about UFOs and related topics, check out the links on the next page.