tau Gem b
tau Gem b is a exoplanet orbiting the K2 III star tau Gem in the constellation Gemini. It lies about 367 light-years from Earth and was discovered in 2013 using the radial velocity method.
Is tau Gem b in the Habitable Zone?
tau Gem b orbits inside the inner edge of the habitable zone of tau Gem. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of tau Gem: 12.407–30.814 AU (conservative: 15.715–29.214 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
See the full interactive habitable-zone view in the Exoplanet Explorer app ›
Orbit and Year Length
A year on tau Gem b — one full orbit around tau Gem — lasts 305.5 Earth days, between the years of Mercury (88 days) and Earth (365 days). It orbits at an average distance of 1.170 AU. Its orbit is nearly circular (eccentricity 0.031).
How Was tau Gem b Discovered?
tau Gem b was discovered in 2013 using the radial velocity method, with observations from Lick 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 tau Gem b?
tau Gem b is 367.0 light-years (112.5 parsecs) from Earth. Light arriving here tonight left the planet around the year 1659. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 6,459,200 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. tau Gem b scores 0.08, ranking #4,722 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: tau Gem
tau Gem
- Spectral type
- K2 III
- Surface temperature
- 4,388 K (Sun: 5,772 K)
- Mass
- 2.30 M☉
- Radius
- 26.80 R☉
- Age
- 1.2 billion years (Sun: 4.6)
Planetary System
tau Gem b is the only planet known to orbit tau Gem so far.
tau Gem b — Complete Data
| Mass (best estimate) | 6,547.00 Earth masses |
|---|---|
| Orbital period | 305.50 days |
| Orbital distance | 1.170 AU |
| Eccentricity | 0.031 |
| Earth Similarity Index | 0.08 |
| Distance from Earth | 367.0 light-years (112.5 parsecs) |
| Constellation | Gemini |
| Discovery method | Radial Velocity |
| Discovery facility | Lick Observatory |
| Discovery year | 2013 |
Data: NASA Exoplanet Archive, last updated 2014-05-14. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About tau Gem b
Is tau Gem b habitable?
No — tau Gem b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is tau Gem b?
tau Gem b is about 367 light-years from Earth in the constellation Gemini. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 6,459,200 years to get there.
How long is a year on tau Gem b?
One orbit around tau Gem takes 305.5 Earth days.
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