Evidence record
How many planets are there?
Every sentence on the exploration belongs to at least one claim below. Each says what kind of statement it is, what it rests on, what the evidence does not establish, and how far it was checked. Nothing here is a score, and none of it is a verdict on a belief or a theory.
Last checked 24 September 2026.
- Partly checked: 2
- Source checked: 31
- A judgement, not a fact: 12
- Presented as open: 1
If something here is wrong, misquoted, out of date or unfair, write to support@unknownoceans.com and give the claim number, which does not change.
What the question takes for granted
A counting question whose answer is a rate: the page separates what has been detected from what the detections imply once the surveys’ blind spots are corrected for, and says where that correction is argued.
Planets around other stars can be counted through their effect on the star
Established
Transits and stellar wobble detect most known planets, and occurrence rates correct for what they miss.
"Planet" has one agreed meaning
Contested
The IAU’s exoplanet definition is a working one: its upper mass limit is a chosen convention, and it excludes objects with no star that the surveys counting them call planets.
A survey of one patch of sky speaks for the galaxy
Open
Kepler watched one field and microlensing looks toward the galactic bulge; the page’s galaxy-wide total extrapolates from both.
The question
Claim: How many planets are there?
- Kind
- Framing. Signposting. It asserts nothing a source could check.
How the question is labelled
Claim: The census
- Kind
- Framing. Signposting. It asserts nothing a source could check.
Claim: Planets
- Kind
- Framing. Signposting. It asserts nothing a source could check.
The question
Claim: Until the 1990s the answer was nine, and every one of them orbited our star.
- Kind
- Historical claim. A statement about the past that historical evidence can test.
- Review
- Partly checked. Only part of the source could be read. What was not read is listed.
Supports
PlutoPluto overview
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: Pluto was long considered our ninth planet, but the International Astronomical Union reclassified Pluto as a dwarf planet in 2006.
Supports
A planetary system around the millisecond pulsar PSR1257 + 12Nature’s summary on the article page
Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Astronomical observation · Measurement
The source reads: these variations were not an artefact, but revealed the presence of two or more planet-sized objects orbiting the neutron star – the first such objects to be detected outside the Solar System
Supports
How We Find and Classify Exoplanetsopening paragraph
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Reference work
The source reads: Since the first confirmation of an exoplanet orbiting a Sun-like star in 1995
What this does not establish
The pulsar paper was read as its abstract and Nature’s summary. "Nine" counts Pluto, which the IAU reclassified in 2006.
Later work looked for
Historical dates; nothing later revises them.
Corrected
24 September 2026. Previously: “Thirty years ago the answer was nine, and every one of them orbited our star.” Thirty years before 2026 is 1996, by which time planets were known around a pulsar (1992) and around 51 Pegasi (1995). Before 1992 the known planets were the Sun’s.
Claim 4 · checked 24 September 2026 · AI-assisted audit
Claim: Thousands of planets have been confirmed around other stars,
- Kind
- Present-day figure. A count, survey or report finding, as the named source gives it.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Planetary Systems Composite ParametersTAP query of the Planetary Systems Composite table, 24 September 2026
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: count(*) 6366
6,366 confirmed planets on the day of the audit.
Later work looked for
NASA Exoplanet Archive queried live on the day of the audit: 6,366 confirmed planets; "thousands" stands.
Claim 5 · checked 24 September 2026 · AI-assisted audit
Claim: and the detected ones are a biased sample of a much larger population.
- Kind
- What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
The Occurrence and Architecture of Exoplanetary Systemssection 1
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: there can be major differences between the observed sample and a truly representative
Supports
One or more bound planets per Milky Way star from microlensing observationsclosing paragraph
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: This result is consistent with every star of the Milky Way hosting (on average) one planet or more in an orbital-distance range of 0.5–10 AU.
Later work looked for
Crossref, 2015 on, "exoplanet occurrence rates review": nothing that changes it; later occurrence work (Bryson and others 2021, read) still corrects for the same selection effects.
Claim 6 · checked 24 September 2026 · AI-assisted audit
Claim: Estimating the true number means correcting for what the methods cannot see, which is where the interesting arguments are.
- Kind
- This page’s reading. A judgement the page makes from the evidence. Others read it differently.
- Review
- A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.
Follows from how an occurrence rate is defined (claim 26) and from the disagreement between teams (claim 28).
Supports
The Occurrence and Architecture of Exoplanetary Systemssection 1
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: to count the number of detected planets with the stipulated properties and ... by the effective number of stars in the survey for which such a planet could have been
Supports
Terrestrial planet occurrence rates for the Kepler GK dwarf samplesection 7, Discussion
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: Further work is needed to understand the differences between our results and the results of Petigura et al. (2013b).
Claim 7 · checked 24 September 2026 · AI-assisted audit
Claim: The first confirmed planet around an ordinary star was found in 1995.
- Kind
- Historical claim. A statement about the past that historical evidence can test.
- Review
- Source checked. The cited passage was read, and it says this.
"Ordinary" in the sense of a star like the Sun, as distinct from the pulsar planets of 1992.
Supports
How We Find and Classify Exoplanetsopening paragraph
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Reference work
The source reads: Since the first confirmation of an exoplanet orbiting a Sun-like star in 1995
Later work looked for
Historical date; nothing later revises it.
Claim 8 · checked 24 September 2026 · AI-assisted audit
Claim: Before that, the only planets known beyond this system’s orbited a pulsar, a spinning neutron star, where two were found in 1992.
- Kind
- Historical claim. A statement about the past that historical evidence can test.
- Review
- Partly checked. Only part of the source could be read. What was not read is listed.
Supports
A planetary system around the millisecond pulsar PSR1257 + 12abstract
Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Astronomical observation · Measurement
The source reads: we demonstrate that, rather than being associated with a stellar object, the pulsar is orbited by two or more planet-sized bodies. The planets detected so far have masses of at least 2.8 M⊕ and 3.4 M⊕
Supports
A planetary system around the millisecond pulsar PSR1257 + 12Nature’s summary on the article page
Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Astronomical observation · Measurement
The source reads: these variations were not an artefact, but revealed the presence of two or more planet-sized objects orbiting the neutron star – the first such objects to be detected outside the Solar System
Supports
A planetary system around the millisecond pulsar PSR1257 + 12abstract
Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Astronomical observation · Measurement
The source reads: rapidly rotating neutron stars
Qualifies
A planetary system around the millisecond pulsar PSR1257 + 12abstract
Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Astronomical observation · Measurement
The source reads: Observations indicate that at least one more planet may be present in this system.
Why the page says two were found in 1992 rather than that only two were known.
What this does not establish
The Nature paper was read as its abstract and the journal’s summary, not in full. The abstract says two planets "or more"; a third was suspected.
Later work looked for
Historical date; nothing later revises it.
Corrected
24 September 2026. Previously: “Before that, the only planetary system anyone could study was this one.” Planets around the pulsar PSR1257+12 were reported in 1992, three years before 51 Pegasi b.
24 September 2026. Previously: “Before that, the only planets known were this system’s and two found in 1992 orbiting a pulsar, a spinning neutron star.” Integrity pass: the old wording made the two 1992 planets the only ones known before 1995. The 1992 abstract reports two or more and says at least one more may be present; the sources support that the known planets beyond the Solar System orbited the pulsar and that two were found in 1992, not that there were only two.
Claim 9 · checked 24 September 2026 · AI-assisted audit
Claim: What has happened since is less a discovery than a census, and like any census the hard part is counting what does not answer the door.
- Kind
- This page’s reading. A judgement the page makes from the evidence. Others read it differently.
- Review
- A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.
The page’s framing of occurrence-rate work, in which undetected planets are counted through detection probabilities.
Supports
The Occurrence and Architecture of Exoplanetary Systemssection 1
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: to count the number of detected planets with the stipulated properties and ... by the effective number of stars in the survey for which such a planet could have been
Claim 10 · checked 24 September 2026 · AI-assisted audit
How a planet is found
Claim: How a planet is found
- Kind
- Framing. Signposting. It asserts nothing a source could check.
Two methods do most of the work
Claim: Two methods do most of the work
- Kind
- Present-day figure. A count, survey or report finding, as the named source gives it.
- Review
- Source checked. The cited passage was read, and it says this.
Transit and radial velocity account for 5,908 of the 6,366 confirmed planets.
Supports
Planetary Systems Composite Parametersthe same table grouped by discovery method
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: "Radial Velocity",1200 "Transit",4708
Of 6,366 confirmed planets, 4,708 were found by transit and 1,200 by radial velocity.
Later work looked for
NASA Exoplanet Archive queried live on the day of the audit: 6,366 confirmed planets; "thousands" stands.
Claim 12 · checked 24 September 2026 · AI-assisted audit
Claim: A planet crossing in front of its star dims it by a tiny, repeating amount.
- Kind
- What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Transits and Occultationssection 4.2
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: The loss of light is only 1% for a Sun-like star crossed by a Jupiter-sized planet, and 0.01% for an Earth-sized planet.
Supports
How We Find and Classify ExoplanetsTransits: Planets Found in Dips in Light
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: Kepler was waiting to catch tiny dips in the amount of light coming from individual stars, caused by planets crossing in front of them.
Later work looked for
How the method works; not a finding later work revises.
Claim 13 · checked 24 September 2026 · AI-assisted audit
Claim: That is the transit method, and it requires the orbit to be lined up almost edge-on from here, which most are not.
- Kind
- What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
- Review
- Source checked. The cited passage was read, and it says this.
For an Earth-like orbit around a Sun-like star the chance of the right alignment is about half a per cent (Winn 2010, equation 11).
Supports
Transits and Occultationssection 2.2, Probability of eclipses
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Theory · Review of the field
The source reads: Eclipses are seen only by privileged observers who view a planet’s orbit nearly edge-on.
Later work looked for
How the method works; not a finding later work revises.
Claim 14 · checked 24 September 2026 · AI-assisted audit
Claim: A planet also pulls its star around a small orbit of its own, shifting the star’s spectrum back and forth.
- Kind
- What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Radial Velocities as an Exoplanet Discovery Methodabstract
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Theory · Review of the field
The source reads: Astronomers measure Doppler shifts in the star’s spectral features, which track the line-of-sight gravitational accelerations of a star caused by the planets orbiting it.
Supports
How We Find and Classify ExoplanetsRadial Velocity: Reading the Wobble
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: The wavelengths of starlight are alternately squeezed and stretched as a star moves slightly closer, then slightly farther away from us.
Later work looked for
How the method works; not a finding later work revises.
Claim 15 · checked 24 September 2026 · AI-assisted audit
Claim: That is the radial velocity method, and it favours heavy planets close in.
- Kind
- What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
- Review
- Source checked. The cited passage was read, and it says this.
The signal grows with the planet’s mass and, more weakly, with a shorter orbit.
Supports
Radial Velocities as an Exoplanet Discovery Methodsection on detectability
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Theory · Review of the field
The source reads: The strongest dependence is on the quantity Mplanet sin i
Supports
Radial Velocities as an Exoplanet Discovery Methodsection on detectability
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Theory · Review of the field
The source reads: were of Jovian planets in short period orbits
Supports
One or more bound planets per Milky Way star from microlensing observationsopening paragraph
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: Both are biased towards planets that are relatively close to their parent stars
Later work looked for
How the method works; not a finding later work revises.
Claim 16 · checked 24 September 2026 · AI-assisted audit
Claim: Both are biased in known directions, which is what makes correcting for them possible.
- Kind
- This page’s reading. A judgement the page makes from the evidence. Others read it differently.
- Review
- A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.
Follows from the occurrence-rate method, which divides by a measured detection probability.
Supports
The Occurrence and Architecture of Exoplanetary Systemssection 1
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: to count the number of detected planets with the stipulated properties and ... by the effective number of stars in the survey for which such a planet could have been
Supports
The Occurrence of Rocky Habitable-zone Planets around Solar-like Stars from Kepler Datasection 1
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: Near the detection limit, both completeness and ... can be low, requiring careful correction
The elided word is "reliability", split across a line in the PDF.
Claim 17 · checked 24 September 2026 · AI-assisted audit
Claim: What a detection actually is
- Kind
- Framing. Signposting. It asserts nothing a source could check.
Claim: A star like the Sun dims by about a per cent or less, repeatedly, on a fixed period.
- Kind
- What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Transits and Occultationssection 4.2
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: The loss of light is only 1% for a Sun-like star crossed by a Jupiter-sized planet, and 0.01% for an Earth-sized planet.
Later work looked for
How the method works; not a finding later work revises.
Corrected
24 September 2026. Previously: “A star dims by a fraction of a per cent, repeatedly, on a fixed period.” A Jupiter-sized planet takes about 1 per cent of a Sun-like star’s light, so "a fraction of a per cent" left out the giants.
24 September 2026. Previously: “A star dims by a per cent or less, repeatedly, on a fixed period.” Integrity pass: the source gives 1 per cent for a Jupiter-sized planet crossing a Sun-like star, not a ceiling for every star; the depth depends on the size of the star as well as the planet.
Claim 19 · checked 24 September 2026 · AI-assisted audit
Claim: An object of a calculable size passes in front of it, once per orbit.
- Kind
- What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Transits and Occultationssection 3.1
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Theory · Review of the field
The source reads: The light curve by itself reveals the planet-to-star radius ratio ... but not the planetary radius
What this does not establish
The dip gives the planet’s size relative to its star; an actual size needs the star’s radius.
Later work looked for
How the method works; not a finding later work revises.
Claim 20 · checked 24 September 2026 · AI-assisted audit
Claim: Spectral lines shift back and forth by metres per second.
- Kind
- What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
- Review
- Source checked. The cited passage was read, and it says this.
The shift is measured as a velocity: about 12 metres per second for Jupiter tugging the Sun.
Supports
Radial Velocities as an Exoplanet Discovery Methodsection on detectability, after equation 6
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Theory · Review of the field
The source reads: Jupiter induces a 12 m/s amplitude motion on the Sun; the Earth’s motion is a (currently) undetectable 9 cm/s.
Later work looked for
How the method works; not a finding later work revises.
Claim 21 · checked 24 September 2026 · AI-assisted audit
Claim: Something with mass is pulling the star around a common centre.
- Kind
- What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Radial Velocities as an Exoplanet Discovery Methodabstract
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Theory · Review of the field
The source reads: Astronomers measure Doppler shifts in the star’s spectral features, which track the line-of-sight gravitational accelerations of a star caused by the planets orbiting it.
Later work looked for
How the method works; not a finding later work revises.
Claim 22 · checked 24 September 2026 · AI-assisted audit
Claim: Neither, for most stars, most of the time.
- Kind
- What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
- Review
- Source checked. The cited passage was read, and it says this.
Most orbits are not aligned to transit, and small planets move their stars by less than instruments can measure.
Supports
Transits and Occultationssection 2.2, Probability of eclipses
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Theory · Review of the field
The source reads: Eclipses are seen only by privileged observers who view a planet’s orbit nearly edge-on.
Supports
Radial Velocities as an Exoplanet Discovery Methodsection on detectability, after equation 6
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Theory · Review of the field
The source reads: Jupiter induces a 12 m/s amplitude motion on the Sun; the Earth’s motion is a (currently) undetectable 9 cm/s.
Later work looked for
How the method works; not a finding later work revises.
Claim 23 · checked 24 September 2026 · AI-assisted audit
Claim: Nothing at all. Absence of a detection is almost never absence of a planet.
- Kind
- This page’s reading. A judgement the page makes from the evidence. Others read it differently.
- Review
- A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.
Follows from planets being the rule around stars (claim 55) and from how rarely an orbit is aligned to transit.
Supports
One or more bound planets per Milky Way star from microlensing observationsclosing paragraph
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: This result is consistent with every star of the Milky Way hosting (on average) one planet or more in an orbital-distance range of 0.5–10 AU.
Supports
Transits and Occultationssection 2.2, Probability of eclipses
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Theory · Review of the field
The source reads: Eclipses are seen only by privileged observers who view a planet’s orbit nearly edge-on.
Claim 24 · checked 24 September 2026 · AI-assisted audit
The correction is the result
Claim: The correction is the result
- Kind
- This page’s reading. A judgement the page makes from the evidence. Others read it differently.
- Review
- A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.
The page’s heading for the claim that the rate, not the raw count, is the finding.
Supports
The Occurrence and Architecture of Exoplanetary Systemssection 1
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: to count the number of detected planets with the stipulated properties and ... by the effective number of stars in the survey for which such a planet could have been
Claim 25 · checked 24 September 2026 · AI-assisted audit
Claim: Take the detections, divide by the probability that each kind of planet would have been detectable, and the answer becomes a rate rather than a count.
- Kind
- What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
The Occurrence and Architecture of Exoplanetary Systemssection 1
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: to count the number of detected planets with the stipulated properties and ... by the effective number of stars in the survey for which such a planet could have been
Later work looked for
How the method works; not a finding later work revises.
Claim 26 · checked 24 September 2026 · AI-assisted audit
Claim: Analyses of the Kepler survey’s Sun-like stars put the occurrence of small planets in modest orbits at a substantial fraction of stars.
- Kind
- Present-day figure. A count, survey or report finding, as the named source gives it.
- Review
- Source checked. The cited passage was read, and it says this.
About half of Sun-like stars for planets of 1 to 4 Earth radii inside a year (Winn and Fabrycky); 0.77 planets per star for 0.75 to 2.5 Earth radii at 50 to 300 days (Burke and others).
Supports
The Occurrence and Architecture of Exoplanetary Systemssection 1, list of occurrence properties, item 4
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: Smaller planets (1-4 R⊕) with P < ∼ 1 year are found around approximately half of Sun-like stars
Supports
Terrestrial planet occurrence rates for the Kepler GK dwarf sampleabstract
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: rate of F0=0.77 planets per star, with an allowed range of 0.3 ≤ F0 ≤1.9
Planets of 0.75 to 2.5 Earth radii with orbits of 50 to 300 days, around Kepler’s GK dwarfs.
Later work looked for
Crossref, 2021 on, "eta-Earth occurrence rate habitable zone Kepler": Bryson and others 2021 (read) correct for reliability as well as completeness and still carry wide, definition-dependent ranges; nothing that removes the disagreement.
Claim 27 · checked 24 September 2026 · AI-assisted audit
Claim: Different teams working from the same data have reached different numbers,
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
Burke and others and Petigura and others both analysed Kepler’s Sun-like stars and disagree significantly.
Supports
Terrestrial planet occurrence rates for the Kepler GK dwarf sampleabstract
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: We generally find higher planet occurrence rates
Supports
Terrestrial planet occurrence rates for the Kepler GK dwarf samplesection 7, Discussion
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: Further work is needed to understand the differences between our results and the results of Petigura et al. (2013b).
Later work looked for
Crossref, 2021 on, "eta-Earth occurrence rate habitable zone Kepler": Bryson and others 2021 (read) correct for reliability as well as completeness and still carry wide, definition-dependent ranges; nothing that removes the disagreement.
Claim 28 · checked 24 September 2026 · AI-assisted audit
Claim: because the correction rests on judgements the data do not settle: how completely faint signals were recovered, how many of them are real, and how large their stars are.
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Terrestrial planet occurrence rates for the Kepler GK dwarf sampleabstract
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: we identify the leading sources of systematics impacting Kepler occurrence rate determinations as: reliability of the planet candidate sample, planet radii, pipeline ... and stellar parameters
The elided word is "completeness", split by the PDF extraction.
Supports
The Occurrence of Rocky Habitable-zone Planets around Solar-like Stars from Kepler Datasection 1
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: Near the detection limit, both completeness and ... can be low, requiring careful correction
The elided word is "reliability", split across a line in the PDF.
What this does not establish
These are the leading systematics one team identifies; it could reproduce a rival result only by combining several of them, and called for further work.
Later work looked for
Crossref, 2021 on, "eta-Earth occurrence rate habitable zone Kepler": Bryson and others 2021 (read) correct for reliability as well as completeness and still carry wide, definition-dependent ranges; nothing that removes the disagreement.
Corrected
24 September 2026. Previously: “because the correction depends on how reliably you think marginal signals were recovered.” Burke and others name four leading systematics: reliability of the candidates, planet radii, pipeline completeness and stellar parameters. The page named one.
Claim 29 · checked 24 September 2026 · AI-assisted audit
What the corrections cannot fix
Claim: What the corrections cannot fix
- Kind
- Framing. Signposting. It asserts nothing a source could check.
How many are in the habitable zone
Claim: How many are in the habitable zone
- Kind
- Framing. Signposting. It asserts nothing a source could check.
Claim: This is the number everyone wants and the one the data support least.
- Kind
- This page’s reading. A judgement the page makes from the evidence. Others read it differently.
- Review
- A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.
Follows from the very few small habitable-zone planets Kepler detected and the wide ranges on every estimate.
Supports
The Occurrence of Rocky Habitable-zone Planets around Solar-like Stars from Kepler Datasection 1
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: Identifying habitable zone rocky planets proved to be a greater challenge than anticipated.
Supports
The Occurrence of Rocky Habitable-zone Planets around Solar-like Stars from Kepler Dataabstract
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: η⊕ for the conservative HZ is between 0.37+0.48 −0.21 (errors reflect 68% credible intervals) and 0.60+0.90 −0.36 planets per star
Claim 32 · checked 24 September 2026 · AI-assisted audit
Claim: It requires extrapolating from planets on short orbits, which are easy to detect, to planets on orbits of a year or more, which are not,
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Terrestrial planet occurrence rates for the Kepler GK dwarf sampleabstract
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: Through extrapolation, we find that the one year orbital period
Supports
The Occurrence of Rocky Habitable-zone Planets around Solar-like Stars from Kepler Dataabstract
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: These bounds reflect two extreme assumptions about the extrapolation of completeness beyond orbital periods where DR25 completeness data are available.
Later work looked for
Crossref, 2021 on, "eta-Earth occurrence rate habitable zone Kepler": Bryson and others 2021 (read) correct for reliability as well as completeness and still carry wide, definition-dependent ranges; nothing that removes the disagreement.
Corrected
24 September 2026. Previously: “It requires extrapolating from planets on short orbits, which are easy to detect, to planets on year-long orbits, which are not, around stars like the Sun rather than the small red stars the surveys favour.” Kepler’s sample was mainly Sun-like stars, not small red ones. The real limit is the one Bryson and others describe: habitable zones beyond Kepler’s longest detectable orbit.
Claim 33 · checked 24 September 2026 · AI-assisted audit
Claim: and for many stars like the Sun the habitable zone lies beyond the longest orbit Kepler could detect.
- Kind
- Present-day figure. A count, survey or report finding, as the named source gives it.
- Review
- Source checked. The cited passage was read, and it says this.
Kepler needed three transits in four years, so about 710 days at most.
Supports
The Occurrence of Rocky Habitable-zone Planets around Solar-like Stars from Kepler Datasection 1
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: period with three transits that can be observed in the four years of Kepler data is 710 days ... Given that the habitable zone of many F and late G stars require orbital periods longer than 710 days, Kepler is not ... of detecting all habitable-zone planets around these stars
What this does not establish
The paper names F and late G stars; stars much like the Sun are near the edge of that range.
Later work looked for
Crossref, 2021 on, "Kepler habitable zone completeness long period": nothing that changes Kepler’s own observing limit.
Claim 34 · checked 24 September 2026 · AI-assisted audit
Claim: Published estimates for how common such planets are differ by more than a factor of ten,
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
Winn and Fabrycky tabulate Kepler-based figures for Sun-like stars from 1.7 to 34 per cent; Burke and others allow 0.01 to 2 planets per star on their own.
Supports
The Occurrence and Architecture of Exoplanetary Systemssection 2.5, Table 2
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: FGK 0.8-2.0 R⊕ 0.3-1.8 2 .8+1.9 ... FGK 0.5-2.0 R⊕ 0.8-1.8 34 ± 14
Two Kepler-based estimates for Sun-like stars in the table: 2.8 per cent and 34 per cent, under different definitions.
Supports
Terrestrial planet occurrence rates for the Kepler GK dwarf sampleabstract
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: planet occurrence rate, ζ1.0=0.1, with an allowed range of 0.01 ≤ ζ1.0 ≤2
Planets within 20 per cent of Earth’s radius and orbital period, reached by extrapolation.
Supports
The Occurrence of Rocky Habitable-zone Planets around Solar-like Stars from Kepler Dataabstract
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: η⊕ for the conservative HZ is between 0.37+0.48 −0.21 (errors reflect 68% credible intervals) and 0.60+0.90 −0.36 planets per star
What this does not establish
Much of the spread is between different definitions of an Earth-like planet and of the habitable zone, not between rival measurements of one quantity.
Later work looked for
Crossref, 2021 on, "eta-Earth occurrence rate habitable zone Kepler": Bryson and others 2021 (read) correct for reliability as well as completeness and still carry wide, definition-dependent ranges; nothing that removes the disagreement.
Corrected
24 September 2026. Previously: “Published estimates for how common such planets are span roughly an order of magnitude, and the spread is honest rather than sloppy.” The review’s table spans 1.7 to 34 per cent for Sun-like stars, a factor of twenty, and one paper’s own allowed range spans a factor of two hundred. The reason for the spread is now given, from the review and from Bryson and others.
Claim 35 · checked 24 September 2026 · AI-assisted audit
Claim: and the spread is honest rather than sloppy:
- Kind
- This page’s reading. A judgement the page makes from the evidence. Others read it differently.
- Review
- A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.
The page’s judgement, following from where the review locates the uncertainty.
Supports
The Occurrence and Architecture of Exoplanetary Systemssection 2.5
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: of the appropriate limits of integration. For example, Petigura et al. (2013) ... results differing by a factor of nine depending on the definition of the habitable zone
Claim 36 · checked 24 September 2026 · AI-assisted audit
Claim: most of it comes from where the habitable zone is drawn and how far the data are stretched.
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
The Occurrence and Architecture of Exoplanetary Systemssection 2.5
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: of the appropriate limits of integration. For example, Petigura et al. (2013) ... results differing by a factor of nine depending on the definition of the habitable zone
Supports
The Occurrence of Rocky Habitable-zone Planets around Solar-like Stars from Kepler Dataabstract
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: These bounds reflect two extreme assumptions about the extrapolation of completeness beyond orbital periods where DR25 completeness data are available.
Later work looked for
Crossref, 2021 on, "eta-Earth occurrence rate habitable zone Kepler": Bryson and others 2021 (read) correct for reliability as well as completeness and still carry wide, definition-dependent ranges; nothing that removes the disagreement.
Claim 37 · checked 24 September 2026 · AI-assisted audit
What counts as a planet
Claim: What counts as a planet
- Kind
- Framing. Signposting. It asserts nothing a source could check.
Claim: The boundary with brown dwarfs is a convention rather than a discovery,
- Kind
- What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
- Review
- Source checked. The cited passage was read, and it says this.
The IAU working definition sets the line at the deuterium-burning mass, about 13 Jupiter masses, and its commission chose to keep it.
Supports
The IAU working definition of an exoplanetsection 2.4, The mass upper limit
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Consensus statement
The source reads: The upper mass limit of the 2003 definition has been controversial (Chabrier et al., 2014), and various proposals have been made to alter it.
Supports
The IAU working definition of an exoplanetsection 2.4
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Consensus statement
The source reads: However, there is no “gap”
Supports
The IAU working definition of an exoplanetsection 2.4
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Consensus statement
The source reads: Finally, the Organizing Committee decided to keep the current mass
Other readings
Some researchers would draw it by formation or at about 25 Jupiter masses; the commission rejected both.
Later work looked for
Working definition as amended in 2018; Crossref, 2022 on, "IAU definition exoplanet": no later amendment found.
Claim 39 · checked 24 September 2026 · AI-assisted audit
Claim: and objects drifting through the galaxy with no star at all may outnumber the stars.
- Kind
- Observation. Something measured or seen, as the named source reports it.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Free-floating planet mass function from the MOA-II nine year surveyabstract
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: This implies a total of f = 21+23 −13 FFP or very wide orbit planets of mass 0.33< M/M⊕ < 6660 per star
Supports
Free-floating planet mass function from the MOA-II nine year surveyabstract
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: Six events are likely to be due to planets
What this does not establish
One microlensing survey, with the count resting on a handful of short events and a mass function fitted to them. Its figure includes planets on very wide orbits that the method cannot tell from unbound ones, and it looked toward the galactic bulge.
Later work looked for
Crossref, 2023 on, "free-floating planet mass function microlensing": follow-up work asks whether individual candidates are unbound or on very wide orbits (Keck imaging, 2023); nothing found that revises the rate, which the page reports as "may".
Corrected
24 September 2026. Previously: “and objects drifting through the galaxy with no star at all are common enough that the word has been stretched to cover them.” The IAU working definition says such objects are not planets, so the word has not been stretched officially; the survey that counts them does use it. The count is 21 per star with a wide range, which is what "common" should say.
Claim 40 · checked 24 September 2026 · AI-assisted audit
Claim: The survey that counted them calls them planets; the IAU’s working definition does not.
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
The definition’s authors propose "free-floating planetary mass objects" as the term.
Supports
Free-floating planet mass function from the MOA-II nine year surveytitle
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: FREE-FLOATING PLANET MASS FUNCTION FROM MOA-II 9-YEAR SURVEY
Supports
The IAU working definition of an exoplanetsection 3.1, item 3
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Consensus statement
The source reads: Free-floating objects in young star clusters with masses ... the limiting mass for thermonuclear fusion of deuterium are not “planets”
Supports
The IAU working definition of an exoplanetsection 2.6
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Consensus statement
The source reads: rather, these objects are often referred to as “free floating planetary mass
Later work looked for
Working definition as amended in 2018; no later amendment found.
Claim 41 · checked 24 September 2026 · AI-assisted audit
Claim: Definitions are not facts about nature, and arguing about them is only useful when the argument changes what gets measured.
- Kind
- This page’s reading. A judgement the page makes from the evidence. Others read it differently.
- Review
- A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.
The page’s view; the definition’s own authors say the word matters less than the physics.
Supports
The IAU working definition of an exoplanetsection 1.1
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Consensus statement
The source reads: Whether or not the word “planet” or “exoplanet” is used for a newly discovered object is much less important for our knowledge than the understanding of its physical characteristics
Claim 42 · checked 24 September 2026 · AI-assisted audit
What they are made of
Claim: What they are made of
- Kind
- Framing. Signposting. It asserts nothing a source could check.
Claim: Absence of a detection is almost never absence of a planet.
- Kind
- This page’s reading. A judgement the page makes from the evidence. Others read it differently.
- Review
- A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.
Repeats the module’s last row: planets are the rule, and most are not aligned or heavy enough to be seen.
Supports
One or more bound planets per Milky Way star from microlensing observationsclosing paragraph
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: This result is consistent with every star of the Milky Way hosting (on average) one planet or more in an orbital-distance range of 0.5–10 AU.
Supports
Transits and Occultationssection 2.2, Probability of eclipses
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Theory · Review of the field
The source reads: Eclipses are seen only by privileged observers who view a planet’s orbit nearly edge-on.
Claim 44 · checked 24 September 2026 · AI-assisted audit
What most of them are like
Claim: What most of them are like
- Kind
- Framing. Signposting. It asserts nothing a source could check.
Claim: The most common kind of planet found so far has no analogue in this solar system: larger than Earth, smaller than Neptune.
- Kind
- Observation. Something measured or seen, as the named source reports it.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
The California-Kepler Survey III: a gap in the radius distribution of small planetssection 1
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: the multitude of planets with radii smaller than Neptune but larger than Earth ... has no example of these intermediate planets, yet they are by far the most common
Supports
The Nature and Origins of Sub-Neptune Size Planetsabstract
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: Planets intermediate in size between the Earth and Neptune, and orbiting closer to their host stars than Mercury does the Sun, are the most common type of planet revealed by exoplanet surveys over the last quarter century.
What this does not establish
Most common among close-in planets, where the surveys can see them; the census of wider orbits is thinner.
Later work looked for
Crossref, 2023 on, "sub-Neptune water world JWST composition": JWST spectra of single planets (TOI-732 c, K2-18 b, 2025) and new interior models keep the composition argued; Kempton and Knutson 2024 (read) find GJ 1214b consistent with either reading.
Claim 46 · checked 24 September 2026 · AI-assisted audit
Claim: The reading with most support is rocky cores wrapped in hydrogen, and some researchers argue for worlds rich in water.
- Kind
- What scholars argue. A report of what specialists argue, or where they disagree.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
The California-Kepler Survey III: a gap in the radius distribution of small planetsabstract
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: supports the emerging picture that close-in planets smaller than Neptune are composed of rocky cores measuring 1.5R⊕ or smaller with varying amounts of low-density gas that determine their total sizes
Supports
The Nature and Origins of Sub-Neptune Size Planetsabstract
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: This bimodality suggests that sub-Neptunes are mostly rocky planets that were born with primary atmospheres a few percent by mass accreted from the protoplanetary nebula.
Supports
The Nature and Origins of Sub-Neptune Size Planetssection 3
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: the mass-loss hypothesis for the nature and origins of sub-Neptune planets currently has the most traction in the field, but alternative
Supports
The Nature and Origins of Sub-Neptune Size Planetssection 3
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: models for the internal structures of individual planets in the 2 – 4 R⊕ regime are degenerate, and thus water-world solutions are possible
Other readings
Water worlds are argued by Zeng and others and Mousis and others, as the review reports; the hydrogen reading explains the radius gap and its trends, which is why it has more support.
Later work looked for
Crossref, 2023 on, "sub-Neptune water world JWST composition": JWST spectra of single planets (TOI-732 c, K2-18 b, 2025) and new interior models keep the composition argued; Kempton and Knutson 2024 (read) find GJ 1214b consistent with either reading.
Corrected
24 September 2026. Previously: “Whether those are rocky worlds with thick atmospheres or small gas envelopes around a core is not settled,” The two options on the page described the same thing, a rocky core under a gas envelope. The argument in the literature is between that reading, which has most support, and water-rich worlds.
Claim 47 · checked 24 September 2026 · AI-assisted audit
Claim: It is not settled,
- Kind
- Open question. Something the page says is not known.
- Review
- Presented as open. The page says this is unresolved, and the review found that it is.
Supports
The Nature and Origins of Sub-Neptune Size Planetssection 3
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: models for the internal structures of individual planets in the 2 – 4 R⊕ regime are degenerate, and thus water-world solutions are possible
Supports
Transiting Exoplanet Atmospheres in the Era of JWSTsection 2.4
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: The derived composition of the planet is consistent with GJ 1214b either being a water world or ‘gas dwarf’
Later work looked for
Crossref, 2023 on, "sub-Neptune water world JWST composition": JWST spectra of single planets (TOI-732 c, K2-18 b, 2025) and new interior models keep the composition argued; Kempton and Knutson 2024 (read) find GJ 1214b consistent with either reading.
Claim 48 · checked 24 September 2026 · AI-assisted audit
Claim: and the answer decides what the commonest planets in the galaxy are made of.
- Kind
- This page’s reading. A judgement the page makes from the evidence. Others read it differently.
- Review
- A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.
Follows from these being the most common planets the surveys find.
Supports
The Nature and Origins of Sub-Neptune Size Planetsabstract
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: Planets intermediate in size between the Earth and Neptune, and orbiting closer to their host stars than Mercury does the Sun, are the most common type of planet revealed by exoplanet surveys over the last quarter century.
Corrected
24 September 2026. Previously: “and the answer changes what the galaxy is mostly made of.” Planets are a tiny share of the galaxy’s matter; the question is what its commonest planets are made of.
Claim 49 · checked 24 September 2026 · AI-assisted audit
Claim: Their atmospheres are now measurable for a handful of favourable cases.
- Kind
- Observation. Something measured or seen, as the named source reports it.
- Review
- Source checked. The cited passage was read, and it says this.
About twenty more sub-Neptunes were scheduled for JWST spectra in its first two cycles, and many earlier spectra were flat.
Supports
Transiting Exoplanet Atmospheres in the Era of JWSTsection 2.4
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: Approximately 20 additional sub-Neptunes are scheduled for transmission spectrum observations with JWST
Supports
Transiting Exoplanet Atmospheres in the Era of JWSTsection 3.3
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: sub-Neptune and super-Earth transmission spectra are consistent with either aerosols or high mean molecular weight atmospheres, leading to degenerate interpretation
Later work looked for
Crossref, 2023 on, "sub-Neptune water world JWST composition": JWST spectra of single planets (TOI-732 c, K2-18 b, 2025) and new interior models keep the composition argued; Kempton and Knutson 2024 (read) find GJ 1214b consistent with either reading.
Corrected
24 September 2026. Previously: “Atmospheres are now measurable for a handful of favourable cases.” Atmospheres of many hot giants have been measured; the handful is true of these planets, so the sentence now says so.
Claim 50 · checked 24 September 2026 · AI-assisted audit
Claim: A handful is not a census.
- Kind
- This page’s reading. A judgement the page makes from the evidence. Others read it differently.
- Review
- A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.
The page’s point, following from the number of planets whose atmospheres have been observed.
Supports
Transiting Exoplanet Atmospheres in the Era of JWSTsection 2.4
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Review of the field
The source reads: Approximately 20 additional sub-Neptunes are scheduled for transmission spectrum observations with JWST
Claim 51 · checked 24 September 2026 · AI-assisted audit
The answer, with its error bars
Claim: The answer, with its error bars
- Kind
- Framing. Signposting. It asserts nothing a source could check.
The number, stated carefully
Claim: The number, stated carefully
- Kind
- Framing. Signposting. It asserts nothing a source could check.
Claim: Thousands are confirmed.
- Kind
- Present-day figure. A count, survey or report finding, as the named source gives it.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
Planetary Systems Composite ParametersTAP query of the Planetary Systems Composite table, 24 September 2026
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: count(*) 6366
6,366 confirmed planets on the day of the audit.
Later work looked for
NASA Exoplanet Archive queried live on the day of the audit: 6,366 confirmed planets; "thousands" stands.
Claim 54 · checked 24 September 2026 · AI-assisted audit
Claim: The corrected rates imply that planets outnumber the more than a hundred billion stars in this galaxy,
- Kind
- Observation. Something measured or seen, as the named source reports it.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
One or more bound planets per Milky Way star from microlensing observationsclosing paragraph
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: on average every star has 1.6+0.72 −0.89
Planets of 5 Earth masses to 10 Jupiter masses at 0.5 to 10 AU.
Supports
One or more bound planets per Milky Way star from microlensing observationsclosing paragraph
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: This result is consistent with every star of the Milky Way hosting (on average) one planet or more in an orbital-distance range of 0.5–10 AU.
Supports
Starsopening section
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Reference work
The source reads: Our Milky Way alone contains more than 100 billion, including our most well-studied star, the Sun.
Supports
Free-floating planet mass function from the MOA-II nine year surveyabstract
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: This implies a total of f = 21+23 −13 FFP or very wide orbit planets
What this does not establish
Cassan and others’ lower bound is below one planet per star; the claim is firmer once free-floating planets are added, which rest on one survey.
Later work looked for
Crossref, 2013 on, "planet occurrence microlensing bound planets per star": nothing found that revises the 1.6 per star; the MOA free-floating count (Sumi and others 2023, read) adds to it rather than replacing it.
Corrected
24 September 2026. Previously: “The corrected rates imply that planets outnumber stars in this galaxy, which puts the total in the hundreds of billions, with an uncertainty that is a factor rather than a percentage.” No cited source gave the galaxy’s star count, so "hundreds of billions" had nothing under it. The star count is now cited from NASA, and NASA’s own total is reported rather than a lower one the page chose.
Claim 55 · checked 24 September 2026 · AI-assisted audit
Claim: and NASA puts the total past a trillion.
- Kind
- Present-day figure. A count, survey or report finding, as the named source gives it.
- Review
- Source checked. The cited passage was read, and it says this.
Supports
How We Find and Classify Exoplanetsopening paragraph
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Reference work
The source reads: A statistical estimate based on data from NASA’s Kepler Space Telescope revealed that there are more planets than stars in our galaxy. That means there are more than a trillion planets in our galaxy alone
What this does not establish
NASA gives the figure without its star count or its range.
Later work looked for
NASA Science page as served on the day of the audit; no revised figure found.
Claim 56 · checked 24 September 2026 · AI-assisted audit
Claim: The uncertainty is a factor rather than a percentage.
- Kind
- Present-day figure. A count, survey or report finding, as the named source gives it.
- Review
- Source checked. The cited passage was read, and it says this.
1.6 planets per star, plus 0.72 or minus 0.89; 21 free-floating planets per star, plus 23 or minus 13.
Supports
One or more bound planets per Milky Way star from microlensing observationsclosing paragraph
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: on average every star has 1.6+0.72 −0.89
Planets of 5 Earth masses to 10 Jupiter masses at 0.5 to 10 AU.
Supports
Free-floating planet mass function from the MOA-II nine year surveyabstract
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: This implies a total of f = 21+23 −13 FFP or very wide orbit planets
Later work looked for
Crossref, 2013 on, "planet occurrence microlensing bound planets per star": nothing found that revises the 1.6 per star; the MOA free-floating count (Sumi and others 2023, read) adds to it rather than replacing it.
Claim 57 · checked 24 September 2026 · AI-assisted audit
Claim: That is a real result and it is not a precise one, and those two things are allowed to be true at once.
- Kind
- This page’s reading. A judgement the page makes from the evidence. Others read it differently.
- Review
- A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.
The page’s reading of a rate whose error bar is as large as the rate.
Supports
One or more bound planets per Milky Way star from microlensing observationsclosing paragraph
Cited · Link answered, 19 October 2026 · The cited passage was read, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: This result is consistent with every star of the Milky Way hosting (on average) one planet or more in an orbital-distance range of 0.5–10 AU.
Claim 58 · checked 24 September 2026 · AI-assisted audit
What was read
- How We Find and Classify ExoplanetsNASA Science · Page as served 24 September 2026Read in full, 24 September 2026 · NASA content; public domain in the United States
- Terrestrial planet occurrence rates for the Kepler GK dwarf sampleBurke and others, The Astrophysical Journal · arXiv:1506.04175v1; read the abstract, section 1 and section 7The cited passage was read, 24 September 2026 · Copyright; quoted brieflyPDF text extraction splits some words; excerpts skip those with " ... ".
- One or more bound planets per Milky Way star from microlensing observationsCassan and others, Nature 481, pages 167 to 169 · arXiv:1202.0903v1; read the opening and closing paragraphsThe cited passage was read, 24 September 2026 · Copyright; quoted briefly
- The California-Kepler Survey III: a gap in the radius distribution of small planetsFulton and others, The Astronomical Journal 154 · arXiv:1703.10375; read the abstract and section 1The cited passage was read, 24 September 2026 · Copyright; quoted briefly
- Free-floating planet mass function from the MOA-II nine year surveySumi and others, The Astronomical Journal 166, article 108 · arXiv:2303.08280v2; read the abstract and section 5The cited passage was read, 24 September 2026 · Copyright; quoted briefly
- PlutoNASA Science · Page as served 24 September 2026Read in full, 24 September 2026 · NASA content; public domain in the United States
- A planetary system around the millisecond pulsar PSR1257 + 12Wolszczan and Frail, Nature 355, pages 145 to 147 · Abstract and the journal’s summary from nature.comAbstract only, 24 September 2026 · Copyright; quoted briefly
- Planetary Systems Composite ParametersNASA Exoplanet Archive · TAP query of the pscomppars table, 24 September 2026, total and by discovery methodRead in full, 24 September 2026A live count that rises as planets are confirmed.
- Transits and OccultationsWinn, in Exoplanets (ed. Seager), University of Arizona Press · arXiv:1001.2010v5; read sections 2.2, 3.1, 4.1 and 4.2The cited passage was read, 24 September 2026 · Copyright; quoted briefly
- Radial Velocities as an Exoplanet Discovery MethodWright, Handbook of Exoplanets, Springer · arXiv:1707.07983v2; read the abstract and the section on detectabilityThe cited passage was read, 24 September 2026 · Copyright; quoted briefly
- The Occurrence and Architecture of Exoplanetary SystemsWinn and Fabrycky, Annual Review of Astronomy and Astrophysics 53, pages 409 to 447 · arXiv:1410.4199v4; read sections 1, 2.2 and 2.5 with Table 2The cited passage was read, 24 September 2026 · Copyright; quoted brieflyPDF text extraction splits some words; excerpts skip those with " ... ".
- The Occurrence of Rocky Habitable-zone Planets around Solar-like Stars from Kepler DataBryson and others, The Astronomical Journal 161, article 36 · arXiv:2010.14812v2; read the abstract and section 1The cited passage was read, 24 September 2026 · Copyright; quoted briefly
- The IAU working definition of an exoplanetLecavelier des Etangs and Lissauer, New Astronomy Reviews 94, article 101641 · arXiv:2203.09520v1; read the abstract and sections 1, 2.4, 2.6, 3 and 4The cited passage was read, 24 September 2026 · Copyright; quoted briefly
- The Nature and Origins of Sub-Neptune Size PlanetsBean, Raymond and Owen, Journal of Geophysical Research: Planets 126 · arXiv:2010.11867v1; read the abstract, plain language summary and sections 1 to 3The cited passage was read, 24 September 2026 · Copyright; quoted briefly
- Transiting Exoplanet Atmospheres in the Era of JWSTKempton and Knutson, Reviews in Mineralogy and Geochemistry 90, pages 411 to 464 · arXiv:2404.15430; read sections 2.4 and 3.3The cited passage was read, 24 September 2026 · Copyright; quoted briefly
- StarsNASA Science · Page as served 24 September 2026; read the opening sectionThe cited passage was read, 24 September 2026 · NASA content; public domain in the United States