The Short Answer
Nobody knows, and anyone who tells you otherwise is selling something. As of 2026 there is no confirmed detection of life beyond Earth: no microbe, no signal, no artifact, no craft. What there is, is a universe far larger and far more planet-rich than anyone guessed when the question was first asked seriously, a short list of hints that have not held up under scrutiny, and a set of instruments that for the first time could plausibly find an answer within a generation.
The question also hides two different questions. "Do aliens exist?" usually means intelligent beings, the kind who might build ships. "Is there life elsewhere?" includes the far more probable case of microbes in a briny ocean under Europa's ice or in the rock of early Mars. Most scientists who work on this would bet on the second and shrug at the first. This article takes both in turn, then deals with the separate matter of whether anyone has visited.
The Numbers: Planets Everywhere
When Frank Drake wrote his equation in 1961, the number of known planets outside the solar system was zero. Today more than 6,000 have been confirmed, and the Kepler mission's statistics say the galaxy holds billions more. Roughly one in five Sun-like stars appears to have a rocky planet in the zone where liquid water can exist, and red dwarfs, the most common stars, host their own crowded systems. The nearest star, Proxima Centauri, has a planet in its habitable zone.
On the ingredients side, the news is the same. Water is common: on Mars in the past, in the oceans of Europa and Enceladus now, in comets, in clouds around newborn stars. Amino acids and nucleobases turn up in meteorites. The raw materials for chemistry like ours are everywhere the telescopes look. None of that is life. It is the reason the question is now taken seriously in agency budgets rather than only at science fiction conventions. See the habitable exoplanets guide and the Drake equation for the arithmetic.
The Hints That Did Not Hold Up (Yet)
Every few years a result is reported as the first evidence of alien life, and every one so far has faded. The 1996 Martian meteorite ALH84001, with its worm-like shapes, is now explained by non-biological chemistry. Phosphine in the clouds of Venus, announced in 2020, shrank under reanalysis to a marginal signal that other teams could not confirm. The exoplanet K2-18b produced the most recent cycle: a 2023 James Webb hint of dimethyl sulfide, a gas made only by life on Earth, followed in April 2025 by a stronger claim from the same Cambridge team, followed within weeks by independent reanalyses that found the signal disappeared under different assumptions about the atmosphere.
The most durable candidate is on Mars. In 2024 the Perseverance rover drilled a rock called Cheyava Falls whose "leopard spot" mineral patterns are the kind of thing microbes leave behind in Earth mudstones, and the peer-reviewed analysis in 2025 called it a potential biosignature, the strongest language a rover result has earned. The catch is that the same spots can form without life, and settling it needs the sample brought home, which the sample-return program's budget troubles have left in doubt. Life on Mars covers the full story.
Sixty Years of Listening
The search for signals began in 1960 with Drake's Project Ozma and has never stopped. The Wow! signal of 1977 remains the only candidate that ever looked right, and a 2024 analysis suggested it may have been a rare natural flare from a hydrogen cloud. Breakthrough Listen has surveyed more than a million stars since 2016 with nothing to show. Millions of home computers sifted Arecibo data for SETI@home between 1999 and 2020 and found no repeating signal. Optical searches for laser flashes and surveys for the waste heat of galaxy-spanning civilizations have come up empty as well.
That silence is the Fermi paradox: if life is common and the galaxy is old, where is everybody? The candidate answers range from "life is rare" to "intelligence is rare" to "civilizations do not last" to "they are quiet on purpose." Each is a serious hypothesis, none is established, and the data so far cannot choose between them. The Fermi paradox and SETI go deeper.
UFOs Are a Separate Question
The evidence for aliens visiting Earth is a different category from the evidence for aliens existing, and it is much weaker. Decades of sightings, from Roswell to the Navy videos, have produced no physical object, no sample, no photograph that survives analysis, and no witness account that cannot be explained by something ordinary. The U.S. government's own review, the AARO historical report of 2024, went through every official program since 1945 and found no evidence that any case involved extraterrestrial technology and no evidence of a cover-up of one. Whistleblowers such as David Grusch dispute that; they have so far offered testimony about what others told them, not evidence.
This does not settle the UAP question, and Congress is right to keep asking what is in restricted airspace. It does mean that "are aliens real?" and "is that light a spaceship?" have different answers. The first is open. The second, for every case that has ever been checked, has been no. The UAP hearings and how to report a sighting cover both sides.
What Would Count as Proof
Scientists have a working standard. For microbes: a biosignature that cannot be produced by known non-biological chemistry, detected by more than one method, ideally in a returned sample. For an exoplanet atmosphere: several gases in a combination that only biology maintains, seen by independent instruments and holding up under different models of the atmosphere. For intelligence: a narrowband signal that repeats and is confirmed by a second observatory, or an artifact examined in a laboratory. Every hint so far fails at least one of those tests, which is why the announcements come with the word "potential."
The next decade has the tools. Europa Clipper arrives in 2030 to sniff the plumes. The Dragonfly rotorcraft reaches Titan in the 2030s. Webb continues to study rocky-planet atmospheres, and the Habitable Worlds Observatory is being designed specifically to image Earth-like planets and look for oxygen and methane together. If life is common, one of these should find it. If none of them do, that will be a result too.
The Honest Answer
Microbial life somewhere else in the universe is, in the judgment of most people who study it, more likely than not; the universe is simply too big and too wet for Earth to be the only place chemistry ever crossed the line. Intelligent life is a genuine unknown, with the silence counting for something. Alien visitors are the least supported of the three claims, with every investigated case explained. Those are three different confidence levels, and keeping them apart is most of what it means to think clearly about the question.
Frequently asked questions
Do aliens exist?
Nobody knows. There is no confirmed detection of life beyond Earth as of 2026. Most scientists consider microbial life somewhere in the universe likely given how common planets and water are, regard intelligent life as an open question, and find no verified evidence that aliens have visited Earth.
Has NASA found aliens?
No. NASA has found potential biosignatures, most notably mineral patterns in a Martian rock drilled by Perseverance in 2024, and hints in exoplanet atmospheres, but none has met the standard for a detection of life. NASA has never announced the discovery of alien life.
What are the odds that aliens exist?
No one can put a real number on it, because the probability that life starts on a suitable planet is unknown. With billions of potentially habitable planets in the Milky Way, even a tiny chance per planet would mean life elsewhere; a small enough chance would leave Earth alone. Finding a second origin of life, even a microbe, would change the estimate more than anything else.
Have aliens visited Earth?
There is no verified evidence that they have. Every UFO case that has been fully investigated has an ordinary explanation or remains simply unidentified, and the 2024 AARO historical review found no evidence of extraterrestrial technology in any U.S. government record. Whistleblower claims to the contrary have not been accompanied by evidence.
What is the closest science has come to finding alien life?
Two results lead: the potential biosignature in the Martian rock Cheyava Falls, published in 2025, and the disputed detections of biology-linked gases on the exoplanet K2-18b. Both are labelled "potential" because non-biological processes can produce the same signals. The 1977 Wow! signal remains the best SETI candidate and has never repeated.