K2-136 d
K2-136 d is a super-Earth orbiting K2-136 in the constellation Taurus. It lies about 193 light-years from Earth and was discovered in 2017 using the transit method.
How Big Is K2-136 d?
K2-136 d has a radius of 1.57 times that of Earth. Its mass is 3.0 times that of Earth, giving it a density of 4.30 g/cm³ — between that of rocky and gaseous planets.
Is K2-136 d in the Habitable Zone?
K2-136 d orbits inside the inner edge of the habitable zone of K2-136. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of K2-136: 0.327–0.808 AU (conservative: 0.414–0.766 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on K2-136 d
The equilibrium temperature of K2-136 d is about 420 K (147 °C) — hotter than anywhere on Earth. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C. It receives 7.07 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on K2-136 d — one full orbit around K2-136 — lasts 25.6 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.154 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.07).
How Was K2-136 d Discovered?
K2-136 d was discovered in 2017 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 K2-136 d?
K2-136 d is 193.2 light-years (59.2 parsecs) from Earth. Light arriving here tonight left the planet around the year 1833. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 3,400,320 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. K2-136 d scores 0.45, ranking #346 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: K2-136
K2-136 d belongs to a system of 2 stars; it orbits K2-136.
K2-136
- Surface temperature
- 4,500 K (Sun: 5,772 K)
- Mass
- 0.74 M☉
- Radius
- 0.68 R☉
- Luminosity
- 0.1673 L☉
- Age
- 0.7 billion years (Sun: 4.6)
The K2-136 Planetary System
K2-136 d is one of 3 known planets in the K2-136 system. Its siblings:
K2-136 d — Complete Data
| Radius | 1.565 Earth radii (0.140 Jupiter radii) |
|---|---|
| Mass | 3.00 Earth masses (0.009 Jupiter masses) |
| Density | 4.30 g/cm³ (Earth: 5.51) |
| Orbital period | 25.58 days |
| Orbital distance | 0.154 AU |
| Eccentricity | 0.071 |
| Equilibrium temperature | 420 K (147 °C) |
| Stellar irradiation | 7.07× Earth |
| Earth Similarity Index | 0.45 |
| Distance from Earth | 193.2 light-years (59.2 parsecs) |
| Constellation | Taurus |
| Discovery method | Transit |
| Discovery facility | K2 |
| Discovery year | 2017 |
Data: NASA Exoplanet Archive, last updated 2023-04-10. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About K2-136 d
Is K2-136 d habitable?
No — K2-136 d orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is K2-136 d?
K2-136 d is about 193 light-years from Earth in the constellation Taurus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 3,400,320 years to get there.
How big is K2-136 d compared to Earth?
K2-136 d has 1.57 times the radius of Earth and about 3.0 times its mass.
How long is a year on K2-136 d?
One orbit around K2-136 takes 25.6 Earth days — short enough that 14 of its years would fit into one Earth year.
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