GJ 3470 b
GJ 3470 b is a Neptune-like planet orbiting GJ 3470 in the constellation Cancer. It lies about 96 light-years from Earth and was discovered in 2012 using the radial velocity method.
How Big Is GJ 3470 b?
GJ 3470 b has a radius of 4.57 times that of Earth. Its mass is 13.9 times that of Earth, giving it a density of 0.80 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is GJ 3470 b in the Habitable Zone?
GJ 3470 b orbits inside the inner edge of the habitable zone of GJ 3470. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of GJ 3470: 0.173–0.448 AU (conservative: 0.220–0.425 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on GJ 3470 b
The equilibrium temperature of GJ 3470 b is about 594 K (320 °C) — hotter than anywhere on Earth. 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 GJ 3470 b — one full orbit around GJ 3470 — lasts 3.34 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.036 AU — closer to its star than Mercury is to the Sun.
How Was GJ 3470 b Discovered?
GJ 3470 b was discovered in 2012 using the radial velocity method, with observations from La Silla 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 GJ 3470 b?
GJ 3470 b is 96.0 light-years (29.4 parsecs) from Earth. Light arriving here tonight left the planet around the year 1930. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 1,689,600 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. GJ 3470 b scores 0.21, ranking #3,791 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: GJ 3470
GJ 3470
- Surface temperature
- 3,600 K (Sun: 5,772 K)
- Mass
- 0.54 M☉
- Radius
- 0.55 R☉
Planetary System
GJ 3470 b is the only planet known to orbit GJ 3470 so far.
GJ 3470 b — Complete Data
| Radius | 4.570 Earth radii (0.408 Jupiter radii) |
|---|---|
| Mass | 13.90 Earth masses (0.044 Jupiter masses) |
| Density | 0.80 g/cm³ (Earth: 5.51) |
| Orbital period | 3.34 days |
| Orbital distance | 0.036 AU |
| Equilibrium temperature | 594 K (320 °C) |
| Earth Similarity Index | 0.21 |
| Distance from Earth | 96.0 light-years (29.4 parsecs) |
| Constellation | Cancer |
| Discovery method | Radial Velocity |
| Discovery facility | La Silla Observatory |
| Discovery year | 2012 |
Data: NASA Exoplanet Archive, last updated 2019-01-28. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About GJ 3470 b
Is GJ 3470 b habitable?
No — GJ 3470 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is GJ 3470 b?
GJ 3470 b is about 96 light-years from Earth in the constellation Cancer. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 1,689,600 years to get there.
How big is GJ 3470 b compared to Earth?
GJ 3470 b has 4.57 times the radius of Earth and about 13.9 times its mass.
How long is a year on GJ 3470 b?
One orbit around GJ 3470 takes 3.3 Earth days — short enough that 109 of its years would fit into one Earth year.
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