KOI-94 c
KOI-94 c is a Neptune-like planet orbiting KOI-94 in the constellation Cygnus. It lies about 1,556 light-years from Earth and was discovered in 2013 using the transit method.
How Big Is KOI-94 c?
KOI-94 c has a radius of 4.32 times that of Earth. Its mass is 15.6 times that of Earth, giving it a density of 0.91 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is KOI-94 c in the Habitable Zone?
KOI-94 c orbits inside the inner edge of the habitable zone of KOI-94. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of KOI-94: 1.271–2.967 AU (conservative: 1.610–2.813 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on KOI-94 c
The equilibrium temperature of KOI-94 c is about 1,012 K (739 °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 KOI-94 c — one full orbit around KOI-94 — lasts 10.4 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.101 AU — closer to its star than Mercury is to the Sun. Its orbit is highly elliptical (eccentricity 0.43), swinging dramatically closer to and farther from its star.
How Was KOI-94 c Discovered?
KOI-94 c was discovered in 2013 using the transit method, with observations from Kepler.
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 KOI-94 c?
KOI-94 c is 1,555.9 light-years (477.1 parsecs) from Earth. Light arriving here tonight left the planet about 1,556 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 27,383,840 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. KOI-94 c scores 0.17, ranking #4,091 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: KOI-94
KOI-94 c belongs to a system of 2 stars; it orbits KOI-94.
KOI-94
- Surface temperature
- 6,182 K (Sun: 5,772 K)
- Mass
- 1.28 M☉
- Radius
- 1.52 R☉
- Luminosity
- 3.0130 L☉
- Age
- 3.2 billion years (Sun: 4.6)
The KOI-94 Planetary System
KOI-94 c is one of 4 known planets in the KOI-94 system. Its siblings:
KOI-94 c — Complete Data
| Radius | 4.320 Earth radii (0.385 Jupiter radii) |
|---|---|
| Mass | 15.60 Earth masses (0.049 Jupiter masses) |
| Density | 0.91 g/cm³ (Earth: 5.51) |
| Orbital period | 10.42 days |
| Orbital distance | 0.101 AU |
| Eccentricity | 0.430 |
| Equilibrium temperature | 1,012 K (739 °C) |
| Earth Similarity Index | 0.17 |
| Distance from Earth | 1,555.9 light-years (477.1 parsecs) |
| Constellation | Cygnus |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2013 |
Data: NASA Exoplanet Archive, last updated 2014-05-14. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About KOI-94 c
Is KOI-94 c habitable?
No — KOI-94 c orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is KOI-94 c?
KOI-94 c is about 1,556 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 27,383,840 years to get there.
How big is KOI-94 c compared to Earth?
KOI-94 c has 4.32 times the radius of Earth and about 15.6 times its mass.
How long is a year on KOI-94 c?
One orbit around KOI-94 takes 10.4 Earth days — short enough that 35 of its years would fit into one Earth year.
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