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an open source database of all discovered extrasolar planets


The planetary system Kepler-18 hosts at least 3 planets.

  System parameters
Primary system name Kepler-18
Alternative system names KOI-137, KIC 8644288
Right ascension 19 52 19.0688
Declination +44 44 46.8075
Distance [parsec] 438±3
Distance [lightyears] 1430±10
Number of stars in system 1
Number of planets in system 3

ArchitectureArchitecture of the system

This list shows all planetary and stellar components in the system. It gives a quick overview of the hierarchical architecture.

  •  Kepler-18, stellar object
    •  Kepler-18 b, planet, semi-major axis: 0.0447 AU
      •  Kepler-18 c, planet, semi-major axis: 0.0752 AU
        •  Kepler-18 d, planet, semi-major axis: 0.1172 AU

        PlanetsPlanets in the system

        This table lists all planets in the system Kepler-18.

          Kepler-18 b Kepler-18 c Kepler-18 d
        Alternative planet names KOI-137 b, KOI-137.03, GSC 03149-02089 b, KIC 8644288 b, 2MASS J19521906+4444467 b, Gaia DR2 2079295583282164992 b KOI-137 c, KOI-137.01, GSC 03149-02089 c, KIC 8644288 c, 2MASS J19521906+4444467 c, Gaia DR2 2079295583282164992 c KOI-137 d, KOI-137.02, KIC 8644288 d, KIC 8644288.02, Gaia DR2 2079295583282164992 d
        Description The Kepler-18 system is hosting at least three transiting planets. It was discovered with the Kepler satellite, and confirmed by a combination of large transit-timing variations, radial-velocity variations, Warm-Spitzer observations, and a statistical analysis of false-positive probabilities.
        Lists Confirmed planets
        Mass [Mjup] 0.0217 0.0540 0.0520
        Mass [Mearth] 6.90 17.16 16.53
        Radius [Rjup] 0.1790 0.490 0.620
        Radius [Rearth] 2.01 5.49 6.95
        Orbital period [days] 3.50 7.64 14.86
        Semi-major axis [AU] 0.0447 0.0752 0.1172
        Eccentricity N/A N/A N/A
        Equilibrium temperature [K] 1182 911 730
        Discovery method transit
        Discovery year 2011
        Last updated [yy/mm/dd] 11/10/05

        starStars in the system

        This table lists all stars in the system Kepler-18.

        Alternative star names KOI-137, KIC 8644288, 2MASS J19521906+4444467, Gaia DR2 2079295583282164992
        Mass [MSun] 0.972
        Radius [RSun] 1.108
        Age [Gyr] N/A
        Metallicity [Fe/H] 0.200
        Temperature [K] 5383
        Spectral type N/A
        Visual magnitude 14.00

        Planet sizes

        The following plot shows the approximate sizes of the planets in this system The Solar System planets are shown as a comparison. Note that unless the radius has been determined through a transit observation, this is only an approximation (see Lissauer et al. 2011b).

        PlutoMercuryMarsVenusEarthNeptuneUranusSaturnJupiterKepler-18 bKepler-18 cKepler-18 d

        Habitable zone

        The following plot shows the approximate location of the planets in this system with respect to the habitable zone (green) and the size of the star (red). This is only an estimate, using the star's spectral type and mass. Note that if no green band is shown in the plot, then the planet's orbit is far outside the habitable zone. The equations of Selsis, Kasting et al are used to draw the inner and outer boundaries.

        Kepler-18 bKepler-18 cKepler-18 d

        referencesScientific references and contributors

        Links to scientific papers and other data sources


        This table lists all links which are relevant to this particular system. Note that this is just a summary. More references to the scientific publications and comments can be found in the commit messages. To see these, head over the github or click here to directly go to the git blame output of this system. In the left column of the output you can see the commit message corresponding to each parameter. It also lists the date of the last commit and the person making the changes. Within the commit message, you will find a link to the scientific publication where the data is taken from. Note that this is a new feature and not all system parameters might have a reference associated with it yet. Please help making this catalogue better and contribute data or references!

        Open Exoplanet Catalogue contributors

        Contributor E-mail Number of commits
        Andrew Tribick ajtribick(at) 2
        Christian Sturm Sol-d(at) 2
        Hanno Rein hanno(at) 7
        Kenneth J Cott kennethjcott(at) 1
        Marc-Antoine ma.martinod(at) 1
        Marc-Antoine Martinod marc-antoine.martinod(at) 2
        Ryan Varley ryanjvarley(at) 2

        This table lists all people who have contributed to the Open Exoplanet Catalogue. Please consider contributing! Click here to find out how. You can also view all commits contributing to this file on github.

        xmlData download

        You can download the xml file corresponding to this planetary system, which is part of the Open Exoplanet Catalogue. All information on this page has been directly generated from this XML file. You can also download the entire catalogue over at github. If you prefer to download the dataset as an ASCII tables, you might find the oec_tables repository useful.


        If you spot an error or if you can contribute additional data to this entry, please send an e-mail to Please include the corrected xml file and a reference to where the new data is coming from, ideally a scientific paper. If you are fluent with git and github, you can also create a pull request or open an issue on the Open Exoplanet Catalogue repository. Please include the reference to the relevant scientific paper in your commit message.