CI Tau c
CI Tau c is a cold gas giant orbiting CI Tau in the constellation Taurus. It lies about 515 light-years from Earth and was discovered in 2024 using the radial velocity method.
Is CI Tau c in the Habitable Zone?
The position of CI Tau c relative to the habitable zone of CI Tau cannot be precisely determined from the available orbital data.
Orbit and Year Length
A year on CI Tau c — one full orbit around CI Tau — lasts 25.2 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.170 AU — closer to its star than Mercury is to the Sun. Its orbit is highly elliptical (eccentricity 0.58), swinging dramatically closer to and farther from its star.
How Was CI Tau c Discovered?
CI Tau c was discovered in 2024 using the radial velocity method, with observations from Multiple Observatories.
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 CI Tau c?
CI Tau c is 515.3 light-years (158.0 parsecs) from Earth. Light arriving here tonight left the planet around the year 1511. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 9,069,280 years to make the journey.
The Host Star: CI Tau
CI Tau
Planetary System
CI Tau c is the only planet known to orbit CI Tau so far.
CI Tau c — Complete Data
| Mass (best estimate) | 1,144.18 Earth masses |
|---|---|
| Orbital period | 25.20 days |
| Orbital distance | 0.170 AU |
| Eccentricity | 0.580 |
| Distance from Earth | 515.3 light-years (158.0 parsecs) |
| Constellation | Taurus |
| Discovery method | Radial Velocity |
| Discovery facility | Multiple Observatories |
| Discovery year | 2024 |
Data: NASA Exoplanet Archive, last updated 2024-04-05. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About CI Tau c
Is CI Tau c habitable?
CI Tau c is not known to orbit within the habitable zone of CI Tau, and as a cold gas giant it is an unlikely candidate for life as we know it.
How far away is CI Tau c?
CI Tau c is about 515 light-years from Earth in the constellation Taurus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 9,069,280 years to get there.
How long is a year on CI Tau c?
One orbit around CI Tau takes 25.2 Earth days — short enough that 14 of its years would fit into one Earth year.
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