The listed value is the approximate present distance from Earth. Interstellar destinations move, but the difference is negligible compared with the enormous journey time at current spacecraft speeds.
Complete world information
K2-18 b
K2-18 b is scientifically important for atmospheric chemistry but its 2.37-Earth radius and high mass make an Earth-like solid surface doubtful.
Scientific status
No exoplanet is confirmed habitable or inhabited. Habitable-zone position only means that liquid surface water could be possible under the right atmospheric conditions. Rate the Earth percentages are editorial comparison scores, not scientific probabilities.
Rate the Earth habitability percentages are editorial comparison scores, not scientific proof of habitability or life.NASA-inspired Hycean artist conceptAtmosphere-rich ocean-world concept
Rate the Earth habitability comparison38%
Optimistic atmospheric candidate — likely sub-Neptune or Hycean-type world
Probability of other life32%
Atmosphere of interest
Minimum delay for information travelling at light speed.
Approximate send-and-reply delay before processing time.
No spacecraft has travelled to this system
Image gallery
K2-18 b observed images and realistic concepts
Real mission or telescope imagery is shown when available; otherwise the closest realistic concept is used and clearly identified.
Photorealistic scientific concept
K2-18 b realistic orbital concept
A high-resolution scientific concept showing how K2-18 b could plausibly appear from orbit.
No resolved true photograph of this world exists, so the site shows a clearly identified realistic concept.Source: Rate the Earth scientific concept generator ↗
Photorealistic scientific concept
K2-18 b surface or atmosphere concept
A second realistic interpretation focused on the surface, clouds, atmosphere or horizon of K2-18 b.
This scene is an editorial scientific visualization, not a claimed photograph.Source: Rate the Earth scientific concept generator ↗Life potential
Could other life exist on K2-18 b?
K2-18 b is not an Earth twin, but its atmospheric observations and possible water-rich environment keep it in active astrobiology discussion.
Atmosphere of interest
Why this score?
- Atmospheric observations make the world scientifically important.
- Its size suggests a complex environment rather than a simple rocky Earth clone.
- Whether stable liquid-water conditions exist remains uncertain.
The score is an editorial and intentionally conservative estimate.
Complete data sheet
Everything listed for K2-18 b
Measured values, estimates, discovery information and the main uncertainties are shown together below.
Travel calculation
How long would the journey take?
Straight-line arithmetic is compared with real mission history. Actual trajectories depend on orbital mechanics, acceleration, braking, launch windows and gravity assists.
A physical reference only. A spacecraft with mass cannot reach light speed.
No operational spacecraft can sustain this interstellar cruise speed.
Still far beyond current spacecraft propulsion.
Parker reaches this speed only very close to the Sun; it is not an interstellar cruise speed.
A comparison using a real high-energy launch from Earth.
A practical comparison with a spacecraft already moving into interstellar space.
Research guide
What we know, and what we do not know
What is directly known
The planet itself is not resolved as a detailed globe. Its existence and properties are inferred mainly through transit, together with measurements of the host star.
What remains unknown
Surface geography, oceans, continents, clouds and living organisms have not been directly observed. Atmosphere and composition may also remain uncertain.
What is known
K2-18 b has a measured radius about 2.37 Earths, a mass near 8.9 Earths and a 32.9-day orbit.
Habitability limits
Its deep atmosphere may separate any ocean from space under pressures unlike Earth, so habitable-zone location does not imply an accessible surface.
Why it stands out
It is among the best-studied temperate exoplanet atmospheres and a major target for JWST chemistry measurements.