September 29, 2026

Kepler-1229 b

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Kepler-1229 b is a rocky exoplanet located approximately 870 light-years away in the constellation Cygnus. It is considered one of the most promising candidates for habitability found during the original Kepler mission.

Key Physical Characteristics

  • Planet Type: Terrestrial (rocky) Super-Earth.
  • Size: It is about 1.4 times the radius of Earth, which is considered a “sweet spot” for planets that are rocky but large enough to hold a thick atmosphere.
  • Orbit: It completes one full orbit around its star every 86.8 Earth days.
  • The Star: Kepler-1229 is a red dwarf star, significantly cooler and smaller than our Sun.

Habitability & Environment

In Lisa Kaltenegger’s research, Kepler-1229 b is a primary example of a world in the conservative habitable zone:

  • Energy Intake: It receives about 60% of the starlight that Earth gets from the Sun. This makes it a “cool Earth,” with energy levels similar to those of Mars.
  • Atmosphere: Because of its larger mass and gravity, it could potentially hold onto a much thicker atmosphere than Mars. With enough greenhouse gases, it could maintain surface temperatures warm enough for liquid water.
  • Tidal Locking: Since its orbit is 87 days—relatively long for a red dwarf planet—it may not be as tightly locked as planets with very short orbits, which could allow for more complex weather patterns.

Scientific Significance

  • Top-Tier Candidate: It consistently ranks high on the Earth Similarity Index because its size and the energy it receives from its star are close to Earth’s proportions.
  • Atmospheric Modeling: Kaltenegger uses this planet to study how Super-Earths orbiting red dwarfs can maintain stable climates. Its distance from the star makes it less likely to suffer from the extreme solar flares that affect closer planets.
  • Discovery: It was discovered using the transit method, where its passage in front of the star provided precise data on its size.