About GJ 229 b
GJ 229 b is a rare exoplanet. It lies about 18.8 light-years from Earth, has an equilibrium temperature near 112 K, spans roughly 3.97 Earth radii and weighs about 14.94 Earth masses.
A deep-frozen world far from its star's warmth.
Rare exoplanet 36 EP
GJ 229 b
RA 92.6436° · Dec -21.8677° · exoplanet
Score breakdown
· 5 badgesRare 46 pts → Epic
- Nearby (<25 ly) +12
- Frozen world +8
- Multi-planet system +6
- Confirmed exoplanet +5
- Sub-Neptune +5
Total score 36
10 more points to reach Epic.
Badges
- Confirmed exoplanet · +5
- Sub-Neptune · +5
- Frozen world · +8
- Multi-planet system · +6
- Nearby (<25 ly) · +12
Trivia
What makes it special
- Frozen world. A deep-frozen world far from its star's warmth.
Could we get there?
- Verdict. Hopelessly far for any craft humanity can build today.
Getting there
- Aboard Voyager 1. ≈ 329.9 thousand years at Voyager 1's speed (17 km/s).
- Fastest probe ever. ≈ 29.3 thousand years even at the Parker Solar Probe's 192 km/s.
- At 10% light speed. ≈ 188 years in a starship at a tenth of light speed.
- Distance. 18.8 light-years from Earth.
Look-back time
- Look-back time. The light you'd see left around the year 2007.
Saying hello
- Say hello. A radio message and its reply would take 37.5 years round-trip.
Standing on it
- A year here. A full year lasts just 579 Earth days.
By the numbers
- Size. About 4× the width of Earth.
- Volume. About 62.6 Earths could fit inside it.
- Mass. About 14.9× the mass of Earth.
- Your weight. You'd weigh about 0.9× your Earth weight standing here.
- Temperature. A frigid -161°C — colder than dry ice.
How we found it
- Discovery. Found by Multiple Observatories using the radial velocity method.
Cosmic context
- Crowded system. One of at least 2 planets orbiting its star.
Properties
- density gcc
- 1.31
- discovery facility
- Multiple Observatories
- discovery method
- Radial Velocity
- dist ly
- 18.7743
- eccentricity
- 0.404
- eq temp k
- 111.85
- insolation
- 0.0237
- mass earth
- 14.9379
- name
- GJ 229 b
- orbital period days
- 579.475
- radius earth
- 3.97
- sys num planets
- 2
How to see it
Like any astronomical target, GJ 229 b is best seen from a dark site away from city lights, and when it is above the horizon depends on your latitude and the time of year. The visibility panel above works out tonight's viewing window for your saved location.
Why GJ 229 b is a rare exoplanet
GJ 229 b scores 36 points on Spacedle's rarity scale, which places it in the rare tier. Another 10 points would lift it into a rarer tier.
That score comes from 5 science badges — Confirmed exoplanet, Sub-Neptune, Frozen world, Multi-planet system and Nearby (<25 ly) — each earned for a real, measurable property of the object. Rarity on Spacedle is never random: the more remarkable an object's astrophysics, the more badges it collects, the higher it scores, and the rarer it ranks.