Imaginary Picture of K2-218 b

Display orbital revolution of K2-218 b around the hoststar K2-218
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Exoplanet Name : K2-218 b
Alternate Name : "2MASS J00511431+0650473 b, EPIC 220503236 b, EPIC 220503236.01, WISE J005114.31+065047.1 b"
Status : Confirmed
Radius (Rjup / Re): 0.2290 (Rjup) 2.5669 (Rearth)
Mass (Mjup / Me): 0.0199 (Mjup) 6.3395 (Mearth)
Semi Major Axis / Orbital Distance Calculated 0.0000 (AU) 0.0840 (AU Est.)
Eccentricity : 0.0000
Orbital Period(Yrs) 0.0238
Orbital Period(Observed/Estimated) 8.68 (Days Obs.) 0.00 (Days Est.)
Surface Gravity (G Earth) 0.9622
Star Radiation at Atmospheric Boundary: 194688.9 (W/m2)
Measured Temperature (K) 0.0 (K)
Blackbody T 0.1(K) 937.5 (K)
Blackbody T 0.3(K) 880.4 (K)
Blackbody T 0.7(K) 712.4 (K)
Tidally Locked Blackbody T 0.1(K) 1114.9 (K)
Tidally Locked Blackbody T 0.3(K) 1047.0 (K)
Size Class: sub-Neptune-size
Mass Class:
Detection Type : Primary Transit
Mass Detection :
Radius Detection :
Habitability by Solar Eq. Astronomical Unit: Not habitable
Habitability by Kopparapu: Not habitable
Star Name : K2-218
Alternate Name : "2MASS J00511431+0650473, EPIC 220503236, WISE J005114.31+065047.1"
Star Distance(LY) : 1268.9
Stellar Radius(Rsun) : 1.0 (Rsun Measured)
Stellar Mass(Msun) : 1.1 (Msun Measured) 1.1 (Msun Estimated)
Star Age : 0.0 (GY)
Temperature : 5757 (K)
Spectral type : G3
UV portion[%]: 7.8
Visible portion[%]: 44.7
IR portion[%]: 47.5
Metalicity : 0.2
Absolute Magnitude: 3.6
Apparent Magnitude: 11.6
Right Ascension(RA) 12.8097
Declination (DEC) 6.8465
Hubble Space Telescope Guide Star Catalog (GSC) ID
Discovered by
Discovery Paper - Authors
Discovery Paper - Title
Discovery Paper - Journal
Discovery Paper - URL
SIMBAD LINK https://simbad.u-strasbg.fr/simbad/sim-basic?Ident=K2-218&submit=SIMBAD+search
Open Exoplanet Database Link
K2-218 b
K2-218 b

  • K2-218 b is an exoplanet orbiting the star K2-218, located about 1268.9 light-years (389.1 pc) away from Solar System. Its discovery was publicly announced on 2018.
  • The host star K2-218 has apparent magnitude of 11.6, with absolute magnitude of 3.6.
  • It is 1.1 times more massive and 1.0 times bigger compared with our Sun. The surface temperature is 5757 with its spectral types of G3
  • In this planetary system, the extrasolar planet K2-218 b orbits around the star K2-218 every 8.7 days with its orbital distance of 0.08 AU ( 12568140.0 km)
  • (Projected orbit of K2-218 b around its host star K2-218)


  • The Star K2-218 's habitable zone is located at the following distance
  • Inner Boundary (the orbital distance at Venus's Equivalent Radiation ) : 0.725 AU ( 108485562.5 km)
  • Earth Boundary (the orbital distance at Earth's Equivalent Radiation) : 1.002 AU ( 149955398.0 km)
  • Outer Boundary (the orbital distance at Mars's Equivalent Radiation) : 1.527 AU ( 228498841.6 km)
  • Snow Line (the orbital distance at Snow Line Equivalent Radiation) : 2.248 AU ( 336246055.2 km)
  • Radiation at Planetary Boundary of K2-218 b : 194688.94 W/m2

    (Habitable zone calculated based on SEAU(Solar Equivalent Astronomical Unit) around the star K2-218)



  • Kopparapu Recent Venus for Star K2-218 distance : 0.753 AU
  • Kopparapu Runaway Greenhouse for Earth-sized planet for Star K2-218 distance : 0.953 AU
  • Kopparapu Runaway Greenhouse for Super-Earth-sized planet for Star K2-218 distance : 0.920 AU
  • Kopparapu Runaway Greenhouse for Mars-sized planet for Star K2-218 distance : 1.009 AU
  • Kopparapu Outer Boundary for Maximum Greenhouse for Star K2-218 distance : 1.684 AU
  • Kopparapu Outer Boundary for Early Mars for Star K2-218 distance : 1.776 AU

    (Habitable zone calculated based on Kopparapu et al.(2013) around the star K2-218)



  • Original Kopparapu Recent Venus for Star K2-218 distance : 0.753 AU
  • Original Kopparapu Runaway Greenhouse for Star K2-218 distance : 0.979 AU
  • Original Kopparapu Moist Greenhouse for Star K2-218 distance : 0.997 AU
  • Original Kopparapu Outer Boundary for Maximum Greenhouse for Star K2-218 distance : 1.713 AU
  • Original Kopparapu Outer Boundary for Early Mars for Star K2-218 distance : 1.782 AU

    (Habitable zone calculated based on Kopparapu et al.(Original) around the star K2-218)



    (Position in Stellar Map of star K2-218 and its Exoplanet K2-218 b)



    (Zoomed position in Stellar Map of star K2-218 and its Exoplanet K2-218 b (zoom level 3))

    (Synthetic Spectrum of star K2-218*)
    *Yamashiki YA et al. 2019 ApJ 881 114
    MUSCLES Paper I - France et al. 2016 ApJ 820 89
    MUSCLES Paper II- Youngblood et al. 2016 ApJ 824 101
    MUSCLES Paper III- Loyd et al. 2016 ApJ 824 102