What counts as confirmed
The NASA Exoplanet Archive includes an object only if it meets all of these tests: a mass, or minimum mass, of 30 Jupiter masses or less; an orbit around a host rather than drifting free; follow-up work that makes a false positive unlikely; and properties published in peer-reviewed papers.
58 of the 6,451 are flagged by the archive as controversial, meaning their existence is disputed in the published work. They stay in this headline count because the archive keeps them. The tables on the habitable zone and extremes pages leave them out.
Why the number moves
The total changes for three reasons. New planets are published. Papers confirm planets that were already on candidate lists. And planets occasionally leave the list or get flagged when later work doubts them. Nobody keeps an official score, so every catalogue sets its own rules, and the archive's rules are set out on its criteria page.
The Extrasolar Planets Encyclopaedia, for example, accepts objects up to 60 Jupiter masses, double the archive's 30 limit. That brings in heavier objects that are close to brown dwarfs. Neither is wrong. They answer slightly different questions.
Planets the archive doubts
Among the 58 flagged planets are all 3 listed for Tau Ceti, a Sun-like star about 12 light years away, and the highly publicized Kepler-186 f and Kepler-452 b. A flag means a published analysis questions the detection. It doesn't prove the planet isn't there, and the flag can be lifted if new data arrives. Radial-velocity signals from nearby stars are an especially common source of doubt, because starspots and flares can mimic small planets.
Two ways to confirm a planet
A planet can be confirmed in two ways. In the first, astronomers measure its mass independently, usually from the star's wobble. In the second, called validation, they show statistically that every other explanation, such as a hidden background binary, is too unlikely. Most of Kepler's planets are validated, not weighed, because their stars are too faint for precise wobble measurements. The archive flags 1,332 planets as detected by both a transit and a wobble. Every other planet rests on one method alone, which is why follow-up work on candidates takes so long.
How the count has grown
The running total passed 1,000 in 2014, 3,000 in 2016 and 5,000 in 2022. The chart uses the discovery year the archive records, so a planet announced late in one year and published the next can shift a year.
The curve has three phases. Until 2013 it climbs slowly: the archive held 911 planets at the end of that year. From 2014 to 2016 it adds 2,531 more, and 2,106 of those (83%) carry Kepler's name, mostly through the batch confirmations described on the discoveries-per-year page. Since the end of 2016 the total has risen by 3,009, an average of about 301 a year, with TESS now the main source.
Planets per star
Most systems have one known planet. That reflects how planets are found, not how stars behave. The methods catch the easiest planets first, so a star with one known planet may well have others we haven't detected.
| Known planets in the system | Systems | Share of systems | Planets |
|---|---|---|---|
| 1 | 3,778 | 77.9% | 3,778 |
| 2 | 720 | 14.9% | 1,440 |
| 3 | 223 | 4.6% | 669 |
| 4 | 83 | 1.7% | 332 |
| 5 | 29 | 0.6% | 145 |
| 6 | 12 | 0.2% | 72 |
| 7 | 1 | 0.0% | 7 |
| 8 | 1 | 0.0% | 8 |
How many are like Earth
6,401 of the 6,451 have a listed radius, although 1,587 of those have never been seen to transit, so their radius isn't a transit measurement. 2,436 have both a radius and a mass or minimum mass. Of those with a radius, 496 are within a quarter of Earth's size, and most of the rest are larger. Exoplanet sizes splits them out, and the habitable zone page asks how many could be rocky and at a temperate distance from their star.
How many we haven't found
The known planets are a sliver of what's out there. A 2012 study in Nature, based on microlensing, estimated that the average star in the Milky Way hosts at least one planet. Estimates of the galaxy's star count start around 100 billion, which would imply hundreds of billions of planets, and the 4,847 stars in this archive are fewer than one in 20,000,000 of them. Treat that as an order of magnitude, since neither side of the comparison is precise.
Which planets we find is shaped by method. The methods page shows how each one favors particular sizes and orbits, and the multi-planet systems page shows that many stars listed with one planet probably have more.
How far away is a typical confirmed planet? The median distance in the archive is 1,138 light years, and the nearest star system with a confirmed planet is 4.2. The nearest exoplanets page lists the closest ones, and the rest of the list reaches across a sizable part of the Milky Way.
Where the count is heading
The archive's TESS list holds 4,820 candidates and its Kepler list holds 1,977. Together they come to 6,797, against 6,451 confirmed planets, but they won't all confirm. Each one has to survive follow-up first, so the confirmed total will keep rising more slowly than the candidate lists suggest.
Questions people ask
How many stars have planets?
The archive lists 4,847 stars or star systems with at least one confirmed planet. That counts discoveries so far. It doesn't say how many stars in the galaxy have planets.
How many exoplanets are Earth-sized?
496 confirmed planets have a radius between 0.8 and 1.25 times Earth's, which is 8% of the 6,401 planets with a listed radius. Size alone doesn't make a planet Earth-like.
How many more candidates are waiting?
The archive's TESS list holds 4,820 planet candidates and its Kepler list holds 1,977. Candidates aren't confirmed planets, and some will turn out to be false alarms.
Do other lists give a different total?
Yes. Catalogues set their own rules, for example on how massive an object can be, so their totals differ. This page uses the NASA Exoplanet Archive and its rules.