Confirmed Exoplanet Discovered 2025

KMT-2023-BLG-2209L b

A gas giant orbiting the unknown KMT-2023-BLG-2209L, located approximately 18,166.9 light-years from Earth.

Key parameters at a glance

  • A radius of 13.90 Earth radii
  • A mass of 254.26 Earth masses
  • Surface gravity around 1.32 g
  • Semi-major axis 3.5100 AU
  • Distance from Earth 18,166.89 light-years
  • Earth Similarity Index 0.291
  • Travel time at Voyager 1 speed 320,373,073 years

KMT-2023-BLG-2209L b Planet Profile

Physical Specs

Radius
13.90 R⊕
Radius (Jupiter)
1.240 R♃
Mass
254.26 M⊕
Mass (Jupiter)
0.800 M♃
Density
0.52 g/cm³
Surface Gravity
1.32 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.291
HZ Position Unknown
Controversial No

Discovery

Year 2025
Method Microlensing
Facility KMTNet
Telescope 1.6 m wide-field telescope

Size rank in cohort

Rank by radius

#456of 1771

top 25.7%

This planet

13.90R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

Metric Earth KMT-2023-BLG-2209L b Jupiter
Radius (R⊕)1.0013.9011.21
Mass (M⊕)1.00254.26317.83
Density (g/cm³)5.510.521.33
Surface Gravity (g)1.001.322.53
Insolation (S⊕)1.000.037

Alternative Mass Estimates

Method Value Interpretation
Best measured mass 254.263 M⊕ Direct mass measurement (not derived).

Percentile among Gas Giant cohort

Radius 13.900 R⊕ · percentile 72 / cohort 1771
Mass 254.263 M⊕ · percentile 27 / cohort 1747
Distance 5,570.00 pc · percentile 94 / cohort 1759
ESI 0.291 · percentile 56 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period
days
Semi-major axis
3.5100 AU
Eccentricity
Inclination
°

Year Length

Orbital period for this planet has not yet been measured.

Eq. Temperature

 

Insolation (S⊕)

Earth = 1.00

Earth Similarity (ESI)

0.291

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Han et al. 2025

Instrument

18k Mosaic CCD camera

Publication

2025-06

Observation locale

Ground

Host System: KMT-2023-BLG-2209L

Spectral Class

Unknown

Effective Temperature

Estimated Age

Stellar Radius

Stellar Mass

0.730 M☉

Metallicity [Fe/H]

Distance
5,570.00 parsec
Light-years 18,166.89 ly
V-band magnitude
mag
Voyager-speed travel 320,373,073 yr

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