Exoplanets · Space Codex
Kepler-452b
Announced in 2015 as a near-Earth twin around a Sun-like star.
An 'Earth cousin' that may not be real
Artist's concept. No telescope has seen Kepler-452b as more than a point of light, and most exoplanets not even that. What we know comes from how a planet dims or tugs its star. Any picture of its surface, colour or sky, anywhere, is an illustration, not an observation.
At a glance
Key points
Later reanalyses questioned the signal, and the Exoplanet Archive now flags it as controversial.
- Possibly not a real planet
- Orbits a Sun-like star every 385 days
- 1.6 times Earth's width
The 2015 announcement
Jon Jenkins and colleagues found the signal by searching all four years of Kepler data. It promised the closest thing yet to an Earth analogue: a 385-day year around a G2 star like the Sun, with about 10% more energy than Earth receives. The paper put the odds against an astrophysical false positive above 99.7%, yet gave only a 49–62% chance that the planet is rocky.
Why it is in doubt
Its transits are shallow and its year is long, so Kepler caught only a few of them in noisy data. Studies in 2018 and 2019 found the validation could not be confirmed, and the archive keeps it listed only until it is definitively refuted or confirmed.
What the reanalyses found
Fergal Mullally and colleagues showed in 2018 that, at this signal strength, Kepler produces far more repeating instrumental blips than genuine transits, so an artefact cannot be ruled out at 99% confidence; they argued it should revert to 'candidate'. Christopher Burke's team reached the same conclusion in 2019 from Kepler's final catalogue. Neither paper proved the signal false. The archive's February 2019 statement keeps the planet listed but marked controversial.
What would settle it
An independent detection: the same 0.02% dip seen by another telescope, or the star's wobble measured. Both are hard. A transit comes only once every 385 days, and the star, at magnitude 13.5, is too faint for the most precise spectrographs to pick up a wobble likely well under a metre per second.
If it exists
At 1.6 Earth radii it would sit near the boundary between rocky super-Earths and gassy mini-Neptunes, around a star older and brighter than the Sun.
Missions
- 2009–2018
Kepler / K2
NASACompletedTransit survey that showed small planets are common.
Related entries
- Kepler-186fFirst Earth-size planet found in a habitable zone
- Exoplanets: the censusPlanets around other stars
Sources
- Mullally et al. 2018, AJ (arXiv) (opens in a new tab)
- Burke et al. 2019, AJ (arXiv) (opens in a new tab)
- NASA Exoplanet Archive: Kepler-452 b status (opens in a new tab)
- NASA Exoplanet Archive: Kepler-452 overview (opens in a new tab)
- Jenkins et al. 2015, AJ 150:56 (arXiv) (opens in a new tab)
Last reviewed against these sources. Built from public NASA, ESA and JPL data; not affiliated with or endorsed by any agency.