K2-154 b
K2-154 b is a super-Earth orbiting K2-154 in the constellation Virgo. It lies about 422 light-years from Earth and was discovered in 2018 using the transit method.
How Big Is K2-154 b?
K2-154 b has a radius of 1.99 times that of Earth.
Is K2-154 b in the Habitable Zone?
K2-154 b orbits inside the inner edge of the habitable zone of K2-154. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of K2-154: 0.256–0.646 AU (conservative: 0.325–0.612 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on K2-154 b
The equilibrium temperature of K2-154 b is about 715 K (442 °C) — hot enough to melt many metals. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C.
Orbit and Year Length
A year on K2-154 b — one full orbit around K2-154 — lasts 3.68 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.041 AU — closer to its star than Mercury is to the Sun.
How Was K2-154 b Discovered?
K2-154 b was discovered in 2018 using the transit method, with observations from K2.
The transit method watches a star for the tiny, regular dip in brightness that occurs when a planet crosses in front of it. The depth and timing of these dips reveal the planet's size and orbital period.
How Far Away Is K2-154 b?
K2-154 b is 421.9 light-years (129.4 parsecs) from Earth. Light arriving here tonight left the planet around the year 1605. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 7,425,440 years to make the journey.
Earth Similarity Index
The Earth Similarity Index (ESI) scores how physically similar a planet is to Earth, from 0 to 1, based on radius, density, escape velocity and surface temperature. K2-154 b scores 0.28, ranking #2,336 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: K2-154
K2-154
- Surface temperature
- 4,097 K (Sun: 5,772 K)
- Mass
- 0.65 M☉
- Radius
- 0.63 R☉
The K2-154 Planetary System
K2-154 b is one of 2 known planets in the K2-154 system. Its siblings:
- K2-154 c (Mini Neptune)
K2-154 b — Complete Data
| Radius | 1.990 Earth radii (0.178 Jupiter radii) |
|---|---|
| Orbital period | 3.68 days |
| Orbital distance | 0.041 AU |
| Equilibrium temperature | 715 K (442 °C) |
| Earth Similarity Index | 0.28 |
| Distance from Earth | 421.9 light-years (129.4 parsecs) |
| Constellation | Virgo |
| Discovery method | Transit |
| Discovery facility | K2 |
| Discovery year | 2018 |
Data: NASA Exoplanet Archive, last updated 2022-03-28. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About K2-154 b
Is K2-154 b habitable?
No — K2-154 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is K2-154 b?
K2-154 b is about 422 light-years from Earth in the constellation Virgo. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 7,425,440 years to get there.
How big is K2-154 b compared to Earth?
K2-154 b has 1.99 times the radius of Earth.
How long is a year on K2-154 b?
One orbit around K2-154 takes 3.7 Earth days — short enough that 99 of its years would fit into one Earth year.
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