Is there life on other planets? As of November 2026, scientists have not found life anywhere beyond Earth, and the search goes on. Alongside that search runs another story, about objects people see in the sky and cannot name. It begins in 1947, when businessman Kenneth Arnold said he saw nine fast objects near Mount Rainier that moved "like saucers skipping on water." A newspaper wrongly described them as saucer-shaped, which gave us the term flying saucer. UFO stands for unidentified flying object: something in the sky that the person who saw it could not identify at that moment.

In June 1947, rancher W.W. Brazel found unusual debris of tinfoil, rubber strips and sticks near Roswell, New Mexico. The Roswell Army Air Field press release said a "flying disc" had been recovered, and a newspaper ran the headline "RAAF Captures Flying Saucer On Ranch in Roswell Region." Almost immediately the military said the "saucer" was a weather balloon carrying a radar target made of foiled paper on a balsa wood frame, though Brazel did not believe the debris was from a weather balloon. In 1994 the Air Force reported that the debris came from Project Mogul, a secret Army Air Forces balloon-borne research project meant to detect Soviet nuclear tests.

The 1997 Air Force report "The Roswell Report: Case Closed" proposed that stories of alien bodies came from other events: crash test dummies dropped from high-altitude balloons, a 1956 KC-97 aircraft accident that killed 11 airmen, and a 1959 manned balloon mishap. The report proposed that witnesses over the years combined these into a few days in July 1947. After a 1980 book called the weather balloon story a cover story, hoaxes followed: the 1984 "Majestic 12" documents were later found to be fake, and a 1995 alien autopsy film was later called a fraud by its director. Many UFO researchers see the Air Force explanations as part of a continued cover-up, and Roswell has become a symbol of UFO and alien stories, with an International UFO Museum opened in 1992 and a UFO festival held there since 1996. The National Archives has not been able to find any documentation about the Roswell incident among the Project Blue Book records.

The U.S. Air Force began Project Sign in 1948, followed by Project Grudge and, in 1952, Project Blue Book. Early investigators thought the objects might be Soviet aircraft, while some researchers suggested spacecraft from other worlds. From 1947 to 1969 the Air Force investigated UFO reports under Blue Book, based at Wright-Patterson Air Force Base, and of 12,618 sightings reported, 701 stayed unidentified. Those 701 included cases with too little information to match a known phenomenon. Each report was classed as identified with an astronomical, atmospheric or human-made cause, or unidentified.

In July 1952 a series of unidentified flying object sightings were reported in Washington, D.C., from July 12 to 29, and the best known of them were on the weekends of July 18-19 and July 26-27. Airport controller Edward Nugent spotted seven objects on his radar, and one object vanished in all three radar centers at the same time. The reports drew the largest Pentagon press conference since World War II, on July 29, 1952. An analysis by the Civil Aeronautics Administration found a temperature inversion, a warm moist layer of air over a cool dry one, in almost every instance, and General Samford said the unknown radar contacts were not caused by solid material objects. Not everyone was convinced by that explanation.

In 1953 the Robertson Panel, led by physicist H.P. Robertson, concluded that 90 percent of sightings could be easily attributed to astronomical or weather phenomena or to ordinary objects such as aircraft, balloons and birds. It dismissed nearly all of the UFO cases it examined and urged the Air Force to strip UFO reports of their special status. The panel grew out of a 1952 CIA memo that warned of mass hysteria and panic, and both the CIA and the Air Force feared an enemy nation could flood the U.S. with false UFO reports, so the concern was about attention and security, not proof of visitors. Parts of its report stayed classified until 1979, which fueled suspicions of a cover-up.

The University of Colorado UFO Project, led by physicist Edward Condon and funded by the Air Force from 1966 to 1968, delivered its report in November 1968, and the Air Force released it in January 1969. It was written by 37 scientists who studied 59 sightings in detail, and it found no evidence of anything other than commonplace phenomena. Condon wrote that nothing from the study of UFOs in 21 years had added to scientific knowledge and that further extensive study probably could not be justified on those grounds. A National Academy of Sciences panel chaired by Gerald Clemence reviewed the report and concluded that no high priority in UFO investigations is warranted by data of the past two decades. The Air Force closed Project Blue Book, begun in March 1952, on December 17, 1969.

Blue Book's conclusions were that no reported UFO was a threat to national security, that no evidence showed unidentified cases used technology beyond modern scientific knowledge, and that no evidence showed they were extraterrestrial vehicles. One cause of reports came to light in 2014, when the CIA declassified a history of its U-2 spy plane program. It showed that U-2 and later OXCART flights accounted for more than half of all UFO reports in the late 1950s and most of the 1960s, a cause the public could not have known about at the time. Ordinary aircraft are also a common cause, because seen from odd angles or in poor light they can look unusual. High-altitude balloons often lack markings and can look strange from certain angles.

The question returned to public view in the 2020s. NASA announced in June 2022 that it would commission an independent study team to examine unidentified anomalous phenomena (UAP) from a scientific perspective, and the team published its final report on September 14, 2023. NASA's study found no evidence that UAPs are extraterrestrial, and it says there are too few high-quality observations to draw scientific conclusions about what such events are. The Pentagon's All-domain Anomaly Resolution Office, called AARO, says many reports are listed as unidentified simply because sensors could not collect enough information to name what was seen. As of November 2026, asked whether it has found any evidence of extraterrestrial technology, AARO answers "No," adding that examination of UAP sightings is ongoing.

The search for life on Mars is a separate line of work. In 1976 NASA's two Viking landers tested Martian soil for signs of biological activity and found nothing definite, but later probes showed that water most likely once flowed on Mars. Curiosity landed on Mars on Aug. 6, 2012, and explores Gale Crater. As of November 2026, it found chemical and mineral evidence of past habitable environments, meaning places where microbial life could have lived. Perseverance launched on July 30, 2020, and landed on Feb. 18, 2021, in Jezero Crater, a crater 28 miles (45 km) wide. As of November 2026, its goals include seeking signs of ancient life and collecting rock samples for possible return to Earth.

In July 2024 Perseverance found a rock called Cheyava Falls in the Bright Angel formation of Jezero Crater. It is about 3.2 by 2 feet and has millimeter-sized off-white splotches ringed with dark material, nicknamed leopard spots. On 10 September 2025 NASA reported a potential biosignature there in a paper in Nature. A potential biosignature is a substance or structure that might have a biological origin but needs more data or further study before scientists can reach a conclusion about life. As of November 2026, scientists say the Cheyava Falls minerals, vivianite and greigite, and its organic matter can be produced by non-biological processes.

Researchers wrote that the source can be resolved only by returning the samples to Earth, so NASA calls the finding a potential biosignature that needs more study, not a discovery of life. Mars Sample Return would bring Perseverance's samples to Earth, but NASA paused the project as of November 13, 2023, and its $11 billion cost was deemed infeasible. In January 2026 Congress's spending law for fiscal year 2026 left the project out. As of November 2026, news reports say it remains cancelled.

Telescopes pursue the same question farther out. As of October 2026, NASA has confirmed more than 6,000 exoplanets, out of billions believed to exist, and some are rogue planets that orbit no star. As of November 2026, Webb Space Telescope data on the planet K2-18 b found water vapour, carbon dioxide and methane in its atmosphere. A 2025 claim of dimethyl sulfide, a possible biosignature, has not been widely accepted as proof of life, and similar molecules can be made by photochemical processes without life.

Nearer to home, Saturn's moon Enceladus has a global ocean inside it. NASA's Cassini spacecraft discovered in 2005 that icy water particles and gas gush from its surface. The moon likely has hydrothermal vents releasing hot, mineral-rich water, so its ocean could be a possible habitat for life, which has not been found. As of November 2026, Europa Clipper, which launched on a SpaceX Falcon Heavy in October 2024, is on its way to study whether Jupiter's moon Europa, which has an ocean under its ice, has conditions that could support life. It begins orbiting Jupiter in April 2030.

The Drake equation, first written as an agenda for discussion at the 1961 Green Bank conference, has seven terms, and it can give a very wide range of answers: in 1961 the conference estimated between 1000 and 100,000,000 civilizations in the Milky Way. Many of its terms are largely or entirely conjecture, so the equation organizes our ignorance and does not make a prediction. The Fermi paradox is the seeming inconsistency between the lack of evidence of extraterrestrial civilizations and the high likelihood that they exist. Scientists have offered many possible answers, and none is confirmed. The Great Filter, introduced by Robin Hanson in 1996, says something natural makes advanced civilizations unlikely to arise. The Rare Earth hypothesis says complex life depends on so many special conditions that it is exceedingly unusual.

One radio signal remains a puzzle. The Wow! signal was a strong, narrow radio signal picked up on August 15, 1977 by Ohio State University's Big Ear telescope, which was searching for extraterrestrial intelligence. It lasted the full 72 seconds the telescope could watch that spot. It has never been heard again, and no explanation has been confirmed. A one-time signal cannot be checked, which is why it stays a puzzle and not evidence of anyone's message. As of November 2026, scientists have not found life anywhere beyond Earth, and the question of whether anything is out there is still open.

Words to know

• biosignature: possible life sign
• inversion: layered air
• declassified: no longer secret
• paradox: puzzling contradiction
• conjecture: educated guess
• hoaxes: tricks or fakes