The K2-18 System
K2-18 is a planetary system in the constellation Leo hosting 2 confirmed exoplanets, about 124 light-years from Earth. One of its planets orbits within the habitable zone, where liquid water could exist on a planetary surface.
Size Comparison: The Planets of K2-18
Planets without a measured radius are not shown.
K2-18: Star and Habitable Zone
K2-18
- Surface temperature
- 3,457 K (Sun: 5,772 K)
- Mass
- 0.36 M☉
- Radius
- 0.41 R☉
Habitable zone of K2-18: 0.120–0.313 AU (conservative: 0.152–0.297 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
See the full interactive habitable-zone view in the Exoplanet Explorer app ›
All 2 Planets in the K2-18 System
Discovery History
The first planet found here, K2-18 b, was discovered in 2015 using the transit method. The most recent addition, K2-18 c, followed in 2017.
Frequently Asked Questions About K2-18
How many planets does K2-18 have?
K2-18 has 2 confirmed exoplanets. More may await discovery.
Are any planets in the K2-18 system habitable?
One planet in the system orbits within the habitable zone, where liquid water could exist. Actual habitability depends on atmospheres and composition, which are not yet known.
How far away is K2-18?
K2-18 is about 124 light-years from Earth in the constellation Leo.
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