HD 240210 b
HD 240210 b is a cold gas giant orbiting the K3 III star HD 240210 in the constellation Cassiopeia. It lies about 1,215 light-years from Earth and was discovered in 2009 using the radial velocity method.
Is HD 240210 b in the Habitable Zone?
HD 240210 b orbits inside the inner edge of the habitable zone of HD 240210. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 240210: 4.795–11.960 AU (conservative: 6.073–11.339 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 HD 240210 b — one full orbit around HD 240210 — lasts 501.8 Earth days, longer than an Earth year. It orbits at an average distance of 1.160 AU. Its orbit is mildly elliptical (eccentricity 0.15).
How Was HD 240210 b Discovered?
HD 240210 b was discovered in 2009 using the radial velocity method, with observations from McDonald 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 HD 240210 b?
HD 240210 b is 1,214.6 light-years (372.4 parsecs) from Earth. Light arriving here tonight left the planet about 1,215 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 21,376,960 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. HD 240210 b scores 0.11, ranking #4,388 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 240210
HD 240210
- Spectral type
- K3 III
- Surface temperature
- 4,297 K (Sun: 5,772 K)
- Mass
- 0.82 M☉
- Luminosity
- 35.4813 L☉
Planetary System
HD 240210 b is the only planet known to orbit HD 240210 so far.
HD 240210 b — Complete Data
| Mass (best estimate) | 1,655.82 Earth masses |
|---|---|
| Orbital period | 501.75 days |
| Orbital distance | 1.160 AU |
| Eccentricity | 0.150 |
| Earth Similarity Index | 0.11 |
| Distance from Earth | 1,214.6 light-years (372.4 parsecs) |
| Constellation | Cassiopeia |
| Discovery method | Radial Velocity |
| Discovery facility | McDonald Observatory |
| Discovery year | 2009 |
Data: NASA Exoplanet Archive, last updated 2014-11-19. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 240210 b
Is HD 240210 b habitable?
No — HD 240210 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 240210 b?
HD 240210 b is about 1,215 light-years from Earth in the constellation Cassiopeia. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 21,376,960 years to get there.
How long is a year on HD 240210 b?
One orbit around HD 240210 takes 501.8 Earth days.
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