TOI-1694 c
TOI-1694 c is a cold gas giant orbiting the K2 V - K3 V star TOI-1694 in the constellation Camelopardalis. It lies about 407 light-years from Earth and was discovered in 2023 using the radial velocity method. It orbits within the habitable zone of its star — the region where liquid water could exist on a planet's surface.
Is TOI-1694 c in the Habitable Zone?
TOI-1694 c orbits inside the conservative habitable zone of TOI-1694 — the region where a rocky planet could sustain liquid water on its surface. This makes it one of the most interesting known exoplanets in the search for life.
Habitable zone of TOI-1694: 0.483–1.168 AU (conservative: 0.612–1.108 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-1694 c
The equilibrium temperature of TOI-1694 c is about 222 K (-51 °C) — well below freezing. 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 TOI-1694 c — one full orbit around TOI-1694 — lasts 386.3 Earth days, longer than an Earth year. It orbits at an average distance of 0.974 AU — comparable to the inner Solar System. Its orbit is mildly elliptical (eccentricity 0.11).
How Was TOI-1694 c Discovered?
TOI-1694 c was discovered in 2023 using the radial velocity method, with observations from W. M. Keck Observatory.
The radial velocity method measures the subtle wobble of a star caused by the gravitational pull of an orbiting planet, visible as periodic shifts in the star's light spectrum. The size of the wobble reveals the planet's minimum mass.
How Far Away Is TOI-1694 c?
TOI-1694 c is 406.7 light-years (124.7 parsecs) from Earth. Light arriving here tonight left the planet around the year 1620. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 7,157,920 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. TOI-1694 c scores 0.32, ranking #1,002 of 5,566 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-1694
TOI-1694
- Spectral type
- K2 V - K3 V
- Surface temperature
- 5,005 K (Sun: 5,772 K)
- Mass
- 0.83 M☉
- Radius
- 0.81 R☉
- Luminosity
- 0.3810 L☉
- Age
- 7.8 billion years (Sun: 4.6)
The TOI-1694 Planetary System
TOI-1694 c is one of 2 known planets in the TOI-1694 system. Its siblings:
- TOI-1694 b (Neptune-like)
TOI-1694 c — Complete Data
| Mass (best estimate) | 316.56 Earth masses |
|---|---|
| Orbital period | 386.25 days |
| Orbital distance | 0.974 AU |
| Eccentricity | 0.111 |
| Equilibrium temperature | 222 K (-51 °C) |
| Earth Similarity Index | 0.32 |
| Distance from Earth | 406.7 light-years (124.7 parsecs) |
| Constellation | Camelopardalis |
| Discovery method | Radial Velocity |
| Discovery facility | W. M. Keck Observatory |
| Discovery year | 2023 |
Data: NASA Exoplanet Archive, last updated 2026-07-09. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-1694 c
Is TOI-1694 c habitable?
TOI-1694 c orbits within the habitable zone of TOI-1694, the region where liquid water could exist on a planet's surface. It sits in the conservative habitable zone — the most promising region for habitability. Whether it is actually habitable depends on its atmosphere and composition, which remain unknown.
How far away is TOI-1694 c?
TOI-1694 c is about 407 light-years from Earth in the constellation Camelopardalis. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 7,157,920 years to get there.
How long is a year on TOI-1694 c?
One orbit around TOI-1694 takes 386.3 Earth days.
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