UFOs and UAP: History, sightings and mysteries

A still from a U.S. Navy video of a UFO sighting.
A still from a U.S. Navy video of a UFO sighting. (Image credit: U.S. Navy)

UFOs are coming out of the shadows.

Discussion of unidentified flying objects — or, as they have recently been rebranded, unidentified aerial phenomena (UAP) — was long relegated to society's fringes. The topic was toxic, and many people avoided serious engagement with it out of fear of being branded a crackpot. 

But that has begun to change in the past few years. Prominent scientists now openly push for serious study of UFOs, and the U.S. Navy recently drew up new guidelines that encourage pilots to report curious or confusing sky sights.

Read on for a brief history of UFO sightings, potential explanations for them and cultural attitudes toward the phenomenon.

Related: 7 things most often mistaken for UFOs

The fascination with the sky and UFOs

People have seen intriguing or confounding objects in the sky for as long as we've been looking up.

Over the eons, for example, many different cultures have regarded meteors and comets as supernatural phenomena, or at least processed them through a supernatural lens. These dramatic sky lights have been deemed manifestations of a deity's displeasure or interpreted as signs that something wonderful, terrible or simply consequential is soon to happen. 

Evidence of this view can be found in the 11th-century Bayeux Tapestry, which chronicles the events leading up to the Norman conquest of England in 1066 CE. The famous Halley's Comet zoomed through the inner solar system that same year, and the 230-foot-long (70 meters) tapestry depicts it blazing ominously above the head of England's King Harold II.

"We see the new king sat on a throne, with nobles to the left and Archbishop Stigand to the right," the Reading Museum wrote in a description of the tapestry's comet scene. (Harold was crowned on Jan. 6, 1066.)  

"At the far side, he is cheered on by the masses," the description continued. "On the far right, Halley's Comet appears in the sky. People think it an evil omen and grow terrified. News of the comet is brought to Harold. Beneath him, a ghostly fleet of ships appears in the lower border, a hint of the Norman invasion to come."

Harold was killed by William the Conqueror's troops during the decisive Battle of Hastings, on Oct. 14, 1066.

UFOs: The early years

The UFO phenomenon as we know it today is much more recent, dating to the era of powered flight. This makes a lot of sense; there weren't nearly as many flying objects to be puzzled by in William the Conqueror's day.

UFOs really took off during World War II, when Allied pilots in both the European and Pacific theaters reported seeing puzzling lights or objects in the sky. They called these curiosities "foo fighters," a term better known today as the band fronted by former Nirvana drummer Dave Grohl.   

Then, in June 1947, American businessman and aviator Kenneth Arnold reported seeing nine shiny, mysterious craft zipping through the skies near Washington's Mount Rainier. Some newspaper stories described these UFOs as "flying disks" or "flying saucers," and the latter term soon wormed its way into the public consciousness.

UFO reports surged in the wake of Arnold's sighting, some of them even winding up in the pages of The New York Times. One of the items the Times picked up was the discovery of some seemingly exotic wreckage on a ranch in Lincoln County, New Mexico in 1947.

In July of that year, a public information officer at the (relatively) nearby Roswell Army Air Field described the debris as a "flying disk," briefly igniting a firestorm of confused interest. Army officials quickly retracted that statement, explaining that the material in question was the remains of a crashed weather balloon, and the "Roswell incident" faded into obscurity. 

(It came roaring back three decades later, however, revived by UFO enthusiasts who claimed that the U.S. government had found an alien spacecraft in New Mexico, perhaps even with extraterrestrials inside, and covered the whole thing up. Some conspiracists believe the wreckage was spirited to a hush-hush military site in southern Nevada called Area 51, where study of the aliens and their craft continues to this day.)

The U.S. military, concerned that some of these UFOs might pose a threat to national security, soon began to investigate sightings systematically. The Air Force established Project Sign to this end in 1947, then followed that with the similarly short-lived Project Grudge in 1948. The more well-known Project Blue Book got started in 1952 and ran all the way to 1969, examining more than 12,600 UFO reports along the way.

One of the sightings Project Blue Book investigated was that of Betty and Barney Hill, who claimed they were captured and examined by extraterrestrials in rural New Hampshire in September 1961. The couple's account started getting picked up by newspapers in 1965, becoming the first-ever widely publicized alien-abduction story, as History.com noted.

Related: UFO watch: 8 times the government looked for flying saucers

UFO reports in modern times

UFO sightings didn't end when Project Blue Book wrapped up, of course; they've kept on rolling in over the decades. 

Some of the most famous ones in the past half-century include that of Travis Walton, an Arizona man whose 1975 alien-abduction claim was dramatized in the 1993 film "Fire in the Sky;" the Rendlesham Forest incident, a string of mysterious observations near England's Royal Air Force Woodbridge station in December 1980; and the Phoenix Lights, which confused many Arizonans in March 1997.

And, in November 2004, several U.S. Navy pilots flying off the coast of San Diego reported seeing bizarre craft zooming through the sky, seemingly maneuvering in ways that exceeded the limits of known technology. Other Navy pilots had similar experiences off the U.S. East Coast a decade later, making a series of intriguing observations from June 2014 to March 2015.

The pilots captured infrared video of some of these encounters using their onboard camera systems. Three of these videos went viral in December 2017 when The New York Times published them as part of a blockbuster story about a previously secret military UFO-investigating effort called the Advanced Aerospace Threat Identification Program, or AATIP for short.

Politico and The Washington Post also published deep dives into AATIP, which was first funded at the request of then-Senator Harry Reid (D-Nev.) and appears to have been a driving force in the rebranding of UFOs to UAP, a term with less historical baggage. The program ran from 2007 until a funding phaseout in 2012, though AATIP personnel have said its work continued in an unofficial capacity for a few years after that.

AATIP has a successor, and it was born in the sunlight, comparatively speaking. In the summer of 2020, the Pentagon announced the establishment of the Unidentified Aerial Phenomena Task Force (UAPTF), whose mission is "to detect, analyze and catalog UAPs that could potentially pose a threat to U.S. national security."

We've seen some of the task force's work already. In June 2021, the Office of the Director of National Intelligence (DNI) released a congressionally mandated report outlining what the UAPTF, the FBI and the Office of Naval Intelligence make of 144 recent UFO encounters documented by U.S. government sensors, with a focus on sightings by Navy pilots between November 2004 and March 2021.  

The report, a preliminary nine-page assessment that you can read here, found that 18 of the 144 UFOs moved in odd or unexpected ways.

"Some UAP appeared to remain stationary in winds aloft, move against the wind, maneuver abruptly or move at considerable speed, without discernible means of propulsion. In a small number of cases, military aircraft systems processed radio frequency (RF) energy associated with UAP sightings," the report states.

Related: What does the Pentagon's new UFO task force mean?

Are UFOs real?

UFOs are undeniably real; people often see things in the sky that they can't identify. But that doesn't necessarily mean there's anything exotic going on.

For example, the 1947 Roswell debris actually came from a high-altitude balloon lofted by the U.S. military as part of Project Mogul, a secret program that searched for evidence of atomic bomb tests by the Soviet Union. And the 1997 Phoenix Lights were likely caused by high-flying planes and a military flare-dropping exercise.  

Alien-abduction stories are more complicated, as they tend to involve more psychological components. But some research suggests that at least some such reports may be explained by lucid dreaming, an odd sleep state in which people can control their dreams.

Project Blue Book got to the bottom of the vast majority of the 12,600 sightings it investigated, ascribing most of them to natural phenomena such as clouds, stars and bright planets. The Air Force researchers could not explain 701 of the encounters, but they concluded that none displayed evidence of otherworldly technology or posed a threat to national security.

The 2021 DNI report evinces less certainty, positively identifying just one of the 144 examined UAP. (That lone demystified object was a large, deflating balloon.) The investigators stressed that more data are needed to understand UAP, which likely have multiple explanations. For example, strange and seemingly inexplicable movement patterns "could be the result of sensor errors, spoofing or observer misperception and require additional rigorous analysis," the report states.

Advanced technology developed by foreign adversaries is another potential cause. If foreign tech is indeed behind some of these sightings, UAP would "represent a national security challenge," the report adds. 

This possibility has spurred the U.S. military to take the UAP issue more seriously than ever before. In 2019, for example, the Navy formalized its UFO-reporting guidelines, a revision that could remove much of the stigma that has long been associated with sightings, as Politico noted.

The 2021 DNI assessment does not explicitly mention the alien hypothesis; it's implicitly lumped into a catch-all "other" category of possible explanations. And there are good reasons not to leap to the E.T. conclusion, experts say.

For example, the Navy pilots' sightings in 2004, 2014 and 2015 occurred in coastal waters, which is where you might expect to find advanced reconnaissance craft operated by rival nations, pointed out Seth Shostak, a senior astronomer at the SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, California. (Flights over the U.S. mainland would be much easier to detect.) And some of the encounters apparently occurred shortly after the Navy jets' radar systems were upgraded, suggesting a glitch of some kind might be responsible.

Indeed, it may be telling that imagery of UFOs, no matter what era it was captured in, tends to depict the objects as fuzzy blobs.

"The sightings always recede to the edge of what technology allows you to do," Shostak told Space.com in 2019. "The aliens are kind of keeping pace with technology."

Common sense also argues for relatively mundane, terrestrial explanations, and not just because of Occam's Razor (the simplest explanation is usually the best one). For example, if some UFOs are indeed alien spacecraft, what exactly are they up to? 

"If the aliens are here, you gotta say they're the best houseguests ever, because they never do anything," Shostak said. "They just buzz around. They don't address climate change; they don't steal our molybdenum."

Related: The search for alien life (reference)

Keeping an open mind on UFOs

Still, the E.T. idea should not be dismissed or ridiculed, Shostak and others argue. It's not very scientific to eliminate a hypothesis out of hand, after all, and some UAP encounters are very difficult to explain.

For example, the November 2004 Navy sightings off the California coast were made by four pilots in two different jets, and they saw the bizarre, fast-moving object with their own eyes, two of the aviators told the CBS news program "60 Minutes" in 2021. That rules out the possibility that an instrument glitch was responsible in that case. And the same UAP was also documented by radar.

"It's not trivial to say what these things are," Shostak said.

There's a growing willingness to entertain all possible explanations, including the alien hypothesis, for such encounters. For example, in July 2021, Harvard astronomer Avi Loeb and colleagues announced a venture called the Galileo Project, which will look for evidence of extraterrestrial civilizations (ETCs) using a network of new telescope systems around the world.

Among other aims, the Galileo Project will attempt to determine the true nature of UAP and odd bodies such as 'Oumuamua, the first interstellar object ever observed in our own solar system. 

'Oumuamua's strangeness led Loeb to suggest that the visitor may be a defunct alien spacecraft. This notion, while still well out of the scientific mainstream, is less outre today than it would have been just a decade or so ago, largely because of the exoplanet revolution. 

In recent years, astronomers have learned that roughly 20% of the Milky Way's 200 billion or so stars probably harbor a rocky planet in their "habitable zone," the range of orbital distances in which liquid water could exist on a world's surface. And a world doesn't have to be in the habitable zone to harbor habitable environments. Multiple moons in our own solar system, such as Jupiter's Europa and Saturn's Enceladus, sport huge oceans beneath their icy shells, after all.

"Given the recently discovered abundance of habitable-zone exoplanets, with potential for extraterrestrial life, the Galileo Project is dedicated to the proposition that humans can no longer ignore the possible existence of ETCs," Loeb said in a July 2021 statement

"Science should not reject potential extraterrestrial explanations because of social stigma or cultural preferences that are not conducive to the scientific method of unbiased, empirical inquiry," he added. "We now must 'dare to look through new telescopes,' both literally and figuratively."

Mike Wall is the author of "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: community@space.com.

Mike Wall
Senior Space Writer

Michael Wall is a Senior Space Writer with Space.com and joined the team in 2010. He primarily covers exoplanets, spaceflight and military space, but has been known to dabble in the space art beat. His book about the search for alien life, "Out There," was published on Nov. 13, 2018. Before becoming a science writer, Michael worked as a herpetologist and wildlife biologist. He has a Ph.D. in evolutionary biology from the University of Sydney, Australia, a bachelor's degree from the University of Arizona, and a graduate certificate in science writing from the University of California, Santa Cruz. To find out what his latest project is, you can follow Michael on Twitter.