Is there life on other planets? What scientists know in 2026

Nobody knows yet. "So far, we have no evidence of life beyond Earth," NASA says. But in 2026 scientists have more good places to look than ever: a Martian rock that may hold signs of ancient microbes, moons with oceans under their ice, and 6,451 confirmed planets around other stars in the NASA Exoplanet Archive (snapshot of 19 October 2026).

How scientists search for life

"So far, the only life we know of is right here on our planet Earth," NASA says. Scientists even admit that "we don't really have a universally accepted definition of life itself". What they look for are signs that life as we know it could exist: liquid water, the right chemistry and a source of energy, and then traces that only living things are likely to leave behind.

There are two ways to search. Spacecraft and rovers can visit places in our own solar system and study rocks, ice and water up close. For planets around other stars, which are far too distant to visit, telescopes such as the James Webb Space Telescope study the gases in their atmospheres. NASA describes how "Webb, or a similar spacecraft in the future, could pick up signs of an atmosphere like our own – oxygen, carbon dioxide, methane". Finding such gases would still need follow-up observations and checks for other explanations.

So the honest answer today: we do not know whether life exists elsewhere, and none has been confirmed, but scientists have not finished looking and some places look promising. One more point: "potentially habitable" means conditions might support some form of life. It does not mean humans could live there without protection.

Mars: a possible sign of ancient life

A promising clue comes from Mars. In July 2024 NASA's Perseverance rover found a reddish rock with pale "leopard spots" in an ancient, dried-up river valley in Jezero crater. The rock is called Cheyava Falls and is about 1 metre long. Perseverance drilled a sample from it, called "Sapphire Canyon".

In September 2025 NASA announced that this sample "contains potential biosignatures", based on a paper in the journal Nature. NASA explains that a potential biosignature "might have a biological origin but requires more data or further study before a conclusion can be reached about the absence or presence of life". The spots contain two iron minerals, vivianite and greigite. On Earth, vivianite is often found around decaying organic matter, and certain microbes can make greigite. But NASA adds: "The minerals also can be generated abiotically, or without the presence of life." Katie Stack Morgan, Perseverance's project scientist, said that "while abiotic explanations for what we see at Bright Angel are less likely given the paper's findings, we cannot rule them out."

So this is not proof of life on Mars, and it is about microbes that may have lived billions of years ago, not life today. NASA released the data so other scientists can "confirm or refute its biological potential". For more about the planet itself, see how far Mars is from Earth and Mars' two moons.

Ocean moons: Europa, Enceladus and Titan

Some of the most promising places are not planets at all but icy moons. Life on Earth needs liquid water, and several moons of Jupiter and Saturn hide water under their ice.

• Europa, a moon of Jupiter: NASA says "a liquid-water ocean with the ingredients for life may lie beneath the frozen crust of Europa". NASA's Europa Clipper launched on 14 October 2024 and is due to reach Jupiter in April 2030, to "determine if Europa has conditions suitable to support life". See Jupiter's moons.
• Enceladus, a moon of Saturn: NASA says it "has a global ocean under a thick, icy shell", and NASA's Cassini spacecraft photographed jets of water ice spraying from its south pole (photo above).
• Titan, Saturn's largest moon: NASA says Titan "could potentially harbor environments with conditions suitable for life", although a 2025 NASA study suggests it may not have a global ocean after all (see our Saturn article). NASA's Dragonfly rotorcraft is planned to launch no earlier than July 2028 and arrive in late 2034. See Saturn's moons.

No life has been confirmed on these moons. They are places where conditions might allow it.

How many planets are there outside our solar system?

On 19 October 2026 the NASA Exoplanet Archive listed 6,451 confirmed exoplanets (planets around other stars). NASA itself says "we've confirmed more than 6,000 exoplanets, out of the billions that we believe exist". The first planets around a Sun-like star were found in the 1990s, and discoveries took off with NASA's Kepler space telescope: 2016 was the record year, with 1,504 new planets in the archive.

Most are found in two ways. About 74% were found by the transit method: a planet passes in front of its star and makes it a tiny bit dimmer. About 19% were found because their gravity makes the star wobble a little (the radial velocity method). Only a small number have been photographed directly. The nearest known exoplanet, Proxima Centauri b, is "still about 4 light-years away", NASA says (a light year is the distance light travels in one year): far too far to visit with today's spacecraft.

How many exoplanets could be habitable?

Nobody can say for sure, because "habitable" does not mean "inhabited". NASA describes the habitable zone as "the distance from a star at which liquid water could exist on orbiting planets' surfaces", also called the "Goldilocks zone".

To get a feel for the numbers, we used a rough size-and-starlight filter on the archive: planets between 0.5 and 1.6 times the width of Earth that receive between 0.25 and 1.5 times as much starlight as Earth. Of the 5,770 planets with both values listed, 32 pass. This is our own screen, not an official list: size and starlight do not tell us the surface temperature, and a planet in that box can still have no air, no water or deadly radiation. For many of these planets the width is not measured but estimated by the archive from the mass. NASA warns that planets close to small red dwarf stars can get X-ray and ultraviolet radiation "up to hundreds of thousands of times more intense than what Earth receives from the Sun".

The nearest planets that pass our filter:

Values from the NASA Exoplanet Archive; some sizes are estimates. The animation below shows how the known planets filled in year by year. The tight orange band near the top partly reflects the archive's estimates of radius from mass, rather than separate measurements of these planets' widths: for many giant planets found by the star-wobble method only the mass is measured, and the archive uses a mass-radius rule (a formula that estimates size from mass). The dots use today's catalogue values, grouped by the year each planet was found.

Which planet has a "99.7% chance of life"? The K2-18 b story

None. The number comes from news about K2-18 b, a planet about 2.4 times as wide as Earth (NASA Exoplanet Archive) that "lies 124 light years away in the constellation of Leo", according to the University of Cambridge. In April 2025 a Cambridge-led team reported hints of dimethyl sulfide (DMS) and/or dimethyl disulfide (DMDS) in its atmosphere, using the James Webb Space Telescope. "On Earth, DMS and DMDS are only produced by life, primarily microbial life such as marine phytoplankton," the university wrote (phytoplankton are tiny organisms living in the ocean). The same release added that "an unknown chemical process may be the source of these molecules".

The university wrote that the observations reached "the 'three-sigma' level of statistical significance". Some headlines turned that into a "99.7% chance of life", but that is not what it means. In a simple bell-curve model of random noise, fluctuations at least as large as three sigma happen about once in 370 tries (chart above). That does not give the chance that this particular result is noise, and it says nothing about whether life exists. To count as a discovery, Cambridge explained, the observations would have to cross the five-sigma threshold (about 1 in 1.7 million in the same simple model), and the team itself said more observations were needed. Even a convincing detection of these gases would not establish life: scientists would still need to check whether chemistry without life could produce them.

Since then, other researchers reanalysed the Webb data. A joint analysis of all Webb instruments "finds insufficient evidence for the presence of DMS and/or DMDS", and found that other molecules "provide an equally good fit to the data". Another study concluded that the planet "does not meet the standards of evidence for life" and that "red noise" (patterns in measurement errors that can look like a signal), rather than a real signal, may explain the mid-infrared hint. For now, K2-18 b is an interesting planet, not a discovery of life.

Earth as a yardstick: how long did life take here?

Earth is the only example we have, so it is a useful yardstick. The US Geological Survey gives "the best age for the Earth" as 4.54 billion years. The oldest confirmed fossils are stromatolites in Western Australia: layered rocks made by "mats of microorganisms living around 3.5 billion years ago", NASA says. So simple life was there within about a billion years of Earth forming, and perhaps earlier, because most of Earth's oldest rocks have been destroyed.

Our own species took much longer. Homo sapiens "evolved in Africa" about 300,000 years ago, according to the Smithsonian. If you squeeze Earth's whole history into one day, Earth forms at midnight, the oldest confirmed fossils appear at about 05:30 in the morning, and humans arrive about 6 seconds before the next midnight (our calculation, chart above).

Our species appeared much later than the earliest known microbes. But one inhabited planet cannot tell us how common life is elsewhere, or how long intelligence usually takes to evolve.

Are we alone in the universe? Listening for other civilizations

Looking for microbes is one search; looking for intelligent life is another. Scientists in SETI (the Search for Extraterrestrial Intelligence) listen with radio telescopes for signals that nature cannot easily make. NASA also mentions another idea: intelligent life "might create atmospheric pollution, as it does on our planet, also detectable from afar". Signs of technology like these are called technosignatures.

No confirmed signal from another civilization has ever been found. NASA's summary is clear: "so far, we have no evidence of life beyond Earth", but also that "there are plenty of planets in the galaxy, many with similarities to our own". Humanity has sent its own message the other way: since 1977 each Voyager spacecraft has carried "a 12-inch gold-plated phonograph record with images and sounds from Earth" (image above).

The universe is about 13.8 billion years old (see how old the universe is), and our searches cover only a tiny part of it. Silence so far does not mean nobody is there.

Life on other planets FAQ

Is there life on other planets? We do not know whether life exists elsewhere, and none has been confirmed. NASA says "so far, we have no evidence of life beyond Earth".

Which planet has a 99.7% chance of life? None. The figure comes from a misreading of a disputed 2025 result for K2-18 b that reached "three sigma". That level describes how rare such a fluctuation would be in a simple model of random noise; it is not a 99.7% chance of life, and later studies found insufficient evidence for the gases.

Is there life on Mars? No life has been found. A rock sample from Jezero crater contains a "potential biosignature" that might come from microbes that lived billions of years ago, or from processes without life (NASA, 2025).

How many exoplanets are there? 6,451 confirmed in the NASA Exoplanet Archive on 19 October 2026; NASA estimates there are billions in our galaxy.

How many exoplanets are habitable? Nobody knows. 32 planets pass our rough size-and-starlight filter, but that does not mean they have water, air or life, or that humans could live there.

What is the closest exoplanet to Earth? Proxima Centauri b, about 4 light years away (NASA). The archive lists it at 4.2 light years, with an 11.2-day orbit.

Which planets in our solar system could support life? Earth is the only one known to. Scientists also study Mars (in the past), and the moons Europa, Enceladus and Titan.

Do humans or aliens exist in other galaxies? No extraterrestrial life has been confirmed in another galaxy. Astronomers can search other galaxies for very powerful technological signals: in 2023, for example, the Breakthrough Listen project reported a radio search of the centres of 97 nearby galaxies. They cannot yet investigate ordinary life on individual planets in other galaxies.

How old is Earth, and how long did life take to appear? Earth is about 4.54 billion years old (USGS). The oldest confirmed fossils are about 3.5 billion years old (NASA), so life was there within about a billion years; Homo sapiens appeared only about 300,000 years ago (Smithsonian).

What is the habitable zone? "The distance from a star at which liquid water could exist on orbiting planets' surfaces," NASA says; it is wider for hotter stars and narrower for small red dwarfs.

How we checked

The exoplanet numbers come from a snapshot of the NASA Exoplanet Archive's Planetary Systems Composite Parameters table, downloaded on 19 October 2026: every confirmed planet with its discovery year and method, size, starlight (insolation) and distance. From that we counted the planets per year and method and applied our rough size-and-starlight filter (0.5-1.6 Earth widths and 0.25-1.5 times Earth's starlight; 5,770 planets have both values above zero). The 32 planets that passed: Proxima Cen b, Ross 128 b, GJ 1061 c, GJ 1061 d, Teegarden's Star b, Teegarden's Star c, GJ 1002 b, GJ 1002 c, GJ 273 b, GJ 667 C f, GJ 667 C e, GJ 3378 b, Wolf 1069 b, L 98-59 f, TRAPPIST-1 d, TRAPPIST-1 e, TRAPPIST-1 f, TRAPPIST-1 g, TOI-700 d, TOI-700 e, LP 890-9 c, TOI-715 b, K2-3 d, K2-72 e, Kepler-1649 c, Kepler-296 e, Kepler-186 f, Kepler-438 b, Kepler-1652 b, Kepler-1229 b, Kepler-62 f, Kepler-442 b. How the numbers add up: of the 6,451 planets, 635 lack a listed size or starlight value, and 46 more have their starlight listed as zero, which leaves 5,770 with both values; the animation plots 5,742 of them, because 28 fall outside its axes (receiving more than 10,000 or less than 0.001 times Earth's starlight, or measuring more than 30 times Earth's width). The download query was: NASA Exoplanet Archive TAP query; results change as the archive is updated. NASA image pages: PIA26344, PIA26368, PIA23645, PIA11688, PIA14113, PIA25330. The archive estimates some sizes from mass, and the count changes as new planets are confirmed.

The Mars result comes from NASA's news release of 10 September 2025 and NASA's image pages; the ocean moons from NASA's Europa Clipper, Jupiter moons, Enceladus and Titan pages (quoted in our Jupiter and Saturn articles); the habitable zone and the search for life from NASA's exoplanet pages; the K2-18 b claim from the University of Cambridge (17 April 2025) and the team's paper, and the reanalyses from two 2025 journal papers (Astronomy & Astrophysics; The Astronomical Journal). The sigma odds are our calculation for a normal distribution. Earth's age comes from the USGS, the oldest confirmed fossils from NASA (2023) and the origin of Homo sapiens from the Smithsonian's Human Origins Program; the one-day timeline is our calculation.

The photos are NASA images; NASA says its images are generally not subject to copyright in the United States, and we credit each one. We did not use artist's impressions of exoplanets. The animation, charts and diagram are our own, made from these numbers. None of the images or videos is AI-generated.