Exoplanet · mini-Neptune
GJ 229 b
GJ 229 b is a mini-Neptune orbiting the star GJ 229. Its year lasts 579 Earth days. It was discovered in 2014 by the Radial Velocity method.
| Host star | GJ 229 |
|---|---|
| Distance | 18.8 light-years (5.76 pc) |
| Orbital period | 579 days |
| Orbital radius | 1.09 AU |
| Eccentricity | 0.404 |
| Radius | 3.97 R⊕ · 0.354 R♃ |
| Mass (minimum) | 14.9 M⊕ · 0.047 M♃ |
| Density | 1.31 g/cm³ |
| Equilibrium temperature | 112 K (-161 °C) |
| Stellar flux received | 0.0237 × Earth |
| Discovery method | Radial Velocity |
| Discovery year | 2014 |
| Discovered by | Multiple Observatories |
Habitable zone
Beyond the habitable zone: it receives only %2.4 of the light the Earth does, a frozen world.
Its star in the sky
In the planet's sky its star is a disc 0.23° across: 0.42 times the Sun as we see it from Earth.
In the sky
Too faint for the naked eye (magnitude 8.15); binoculars will find it. Visible from the whole Southern Hemisphere and north to latitude 68° N. South of latitude 68° S it never sets. It stands highest at midnight in December, the best time to observe it.
Light's journey
The light you see tonight set out around the year 2007. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 333 thousand years.
Planets in the same system
- GJ 229 A c 122-day orbit · 2.87 R⊕
Data: NASA Exoplanet Archive, PSCompPars. Its look in the simulation is a rendering based on the measured radius, mass and temperature.