Ross 176 b
Ross 176 b is a super-Earth orbiting the K7 V star Ross 176 in the constellation Cygnus. It lies about 152 light-years from Earth and was discovered in 2025 using the transit method.
How Big Is Ross 176 b?
Ross 176 b has a radius of 1.84 times that of Earth. Its mass is 4.6 times that of Earth, giving it a density of 4.03 g/cm³ — between that of rocky and gaseous planets.
Is Ross 176 b in the Habitable Zone?
Ross 176 b orbits inside the inner edge of the habitable zone of Ross 176. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Ross 176: 0.226–0.571 AU (conservative: 0.286–0.541 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 ›
Temperature on Ross 176 b
The equilibrium temperature of Ross 176 b is about 682 K (409 °C) — hot enough to melt many metals. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C. It receives 36.20 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on Ross 176 b — one full orbit around Ross 176 — lasts 5.01 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.046 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.25).
How Was Ross 176 b Discovered?
Ross 176 b was discovered in 2025 using the transit method, with observations from Transiting Exoplanet Survey Satellite (TESS).
The transit method watches a star for the tiny, regular dip in brightness that occurs when a planet crosses in front of it. The depth and timing of these dips reveal the planet's size and orbital period.
How Far Away Is Ross 176 b?
Ross 176 b is 151.5 light-years (46.4 parsecs) from Earth. Light arriving here tonight left the planet around the year 1875. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 2,666,400 years to make the journey.
The Host Star: Ross 176
Ross 176
- Spectral type
- K7 V
- Surface temperature
- 4,041 K (Sun: 5,772 K)
- Mass
- 0.58 M☉
- Radius
- 0.57 R☉
- Luminosity
- 0.0778 L☉
- Age
- 3.0 billion years (Sun: 4.6)
Planetary System
Ross 176 b is the only planet known to orbit Ross 176 so far.
Ross 176 b — Complete Data
| Radius | 1.840 Earth radii (0.164 Jupiter radii) |
|---|---|
| Mass | 4.57 Earth masses (0.014 Jupiter masses) |
| Density | 4.03 g/cm³ (Earth: 5.51) |
| Orbital period | 5.01 days |
| Orbital distance | 0.046 AU |
| Eccentricity | 0.250 |
| Equilibrium temperature | 682 K (409 °C) |
| Stellar irradiation | 36.20× Earth |
| Distance from Earth | 151.5 light-years (46.4 parsecs) |
| Constellation | Cygnus |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2025 |
Data: NASA Exoplanet Archive, last updated 2025-08-14. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Ross 176 b
Is Ross 176 b habitable?
No — Ross 176 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Ross 176 b?
Ross 176 b is about 152 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 2,666,400 years to get there.
How big is Ross 176 b compared to Earth?
Ross 176 b has 1.84 times the radius of Earth and about 4.6 times its mass.
How long is a year on Ross 176 b?
One orbit around Ross 176 takes 5.0 Earth days — short enough that 73 of its years would fit into one Earth year.
Explore Ross 176 b in the app
Browse, filter and compare 6,000+ exoplanets on iPhone, iPad and Apple Watch — with habitable-zone views, widgets and offline data.
