K2-19 d
K2-19 d is a terrestrial planet orbiting K2-19 in the constellation Virgo. It lies about 945 light-years from Earth and was discovered in 2016 using the transit method.
How Big Is K2-19 d?
K2-19 d has a radius of 1.04 times that of Earth. Its mass is 6.2 times that of Earth, giving it a density of 31.00 g/cm³ — comparable to rocky planets like Earth (5.51 g/cm³).
Is K2-19 d in the Habitable Zone?
K2-19 d orbits inside the inner edge of the habitable zone of K2-19. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of K2-19: 0.536–1.280 AU (conservative: 0.679–1.214 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on K2-19 d
The equilibrium temperature of K2-19 d is about 1,258 K (985 °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 K2-19 d — one full orbit around K2-19 — lasts 2.51 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.035 AU — closer to its star than Mercury is to the Sun. Its orbit is highly elliptical (eccentricity 0.44), swinging dramatically closer to and farther from its star.
How Was K2-19 d Discovered?
K2-19 d was discovered in 2016 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 K2-19 d?
K2-19 d is 945.3 light-years (289.8 parsecs) from Earth. Light arriving here tonight left the planet around the year 1081. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 16,637,280 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. K2-19 d scores 0.30, ranking #1,547 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: K2-19
K2-19
- Surface temperature
- 5,322 K (Sun: 5,772 K)
- Mass
- 0.88 M☉
- Radius
- 0.82 R☉
The K2-19 Planetary System
K2-19 d is one of 3 known planets in the K2-19 system. Its siblings:
K2-19 d — Complete Data
| Radius | 1.044 Earth radii (0.093 Jupiter radii) |
|---|---|
| Mass | 6.20 Earth masses (0.020 Jupiter masses) |
| Density | 31.00 g/cm³ (Earth: 5.51) |
| Orbital period | 2.51 days |
| Orbital distance | 0.035 AU |
| Eccentricity | 0.440 |
| Equilibrium temperature | 1,258 K (985 °C) |
| Earth Similarity Index | 0.30 |
| Distance from Earth | 945.3 light-years (289.8 parsecs) |
| Constellation | Virgo |
| Discovery method | Transit |
| Discovery facility | K2 |
| Discovery year | 2016 |
Data: NASA Exoplanet Archive, last updated 2026-03-26. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About K2-19 d
Is K2-19 d habitable?
No — K2-19 d orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is K2-19 d?
K2-19 d is about 945 light-years from Earth in the constellation Virgo. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 16,637,280 years to get there.
How big is K2-19 d compared to Earth?
K2-19 d has 1.04 times the radius of Earth and about 6.2 times its mass.
How long is a year on K2-19 d?
One orbit around K2-19 takes 2.5 Earth days — short enough that 146 of its years would fit into one Earth year.
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