Confirmed exoplanet · Database record + computed analysis
K2-154 c
A confirmed world orbiting K2-154, 421.9 light-years away.
A sub-Neptune
2.07 Earth radii, likely a rocky core under a thick gas or steam envelope rather than a walkable surface.
The orbit
Its year, one full orbit, takes just 8.0 Earth days. Orbiting this tightly around a cool star, it is very likely tidally locked: one hemisphere in permanent day, the other in permanent night.
Temperature and starlight
Its equilibrium temperature (the airless-world estimate) is about 279 °C. Above water's boiling point. It receives 20.5 times the starlight Earth gets.
Its sun
Its star is an orange K-type (4,097 K), M0.0 V: cooler and longer-lived than the Sun, a class some astronomers consider ideal for habitability. It shares the system with 1 other known planet.
How far is that, really?
At 422 light-years, tonight's light from this system left it around the year 1604. A Voyager-speed probe would need roughly 7,464,555 years to get there.
How we found it
It was found by the transit method: the planet crosses its star's face on schedule, dimming it by a tiny, repeating fraction. The dip's depth gives the planet's size. The discovery was announced in 2018 from K2.
Everything above is computed from the archive’s measured values for this planet. Where a quantity is missing, the statement is omitted rather than guessed.
About this record
The measured values come from the NASA Exoplanet Archive, and any missing value has not been determined yet; the Atlas never fills gaps with guesses. More standout worlds: Proxima b, TRAPPIST-1e, K2-18 b, 55 Cancri e, and the detection methods that found them all.