Confirmed Exoplanet Discovered 2026

KMT-2025-BLG-0121L b

A gas giant orbiting the unknown KMT-2025-BLG-0121L, located approximately 20,221.7 light-years from Earth.

Key parameters at a glance

  • A radius of 12.60 Earth radii
  • A mass of 2,469.53 Earth masses
  • Surface gravity around 15.56 g
  • Semi-major axis 3.0500 AU
  • Distance from Earth 20,221.67 light-years
  • Earth Similarity Index 0.418
  • Travel time at Voyager 1 speed 356,609,166 years

KMT-2025-BLG-0121L b Planet Profile

Physical Specs

Radius
12.60 R⊕
Radius (Jupiter)
1.130 R♃
Mass
2,469.53 M⊕
Mass (Jupiter)
7.770 M♃
Density
6.78 g/cm³
Surface Gravity
15.56 g (Earth)

Classification

Planet Type

Gas Giant

ESI Score 0.418
HZ Position Unknown
Controversial No

Discovery

Year 2026
Method Microlensing
Facility KMTNet
Telescope 1.6 m wide-field telescope

Size rank in cohort

Rank by radius

#1179of 1771

top 66.5%

This planet

12.60R⊕

Gas Giant median

13.52R⊕

Nearest-size peers

Metric Earth KMT-2025-BLG-0121L b Jupiter
Radius (R⊕)1.0012.6011.21
Mass (M⊕)1.002,469.53317.83
Density (g/cm³)5.516.781.33
Surface Gravity (g)1.0015.562.53
Insolation (S⊕)1.000.037

Alternative Mass Estimates

Method Value Interpretation
Best measured mass 2,469.527 M⊕ Direct mass measurement (not derived).

Percentile among Gas Giant cohort

Radius 12.600 R⊕ · percentile 31 / cohort 1771
Mass 2,469.527 M⊕ · percentile 83 / cohort 1747
Distance 6,200.00 pc · percentile 95 / cohort 1759
ESI 0.418 · percentile 91 / cohort 1771

Orbit & Habitability

Orbital Dynamics

Period
days
Semi-major axis
3.0500 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)

0.418

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Han et al. 2026

Instrument

18k Mosaic CCD camera

Publication

2026-02

Observation locale

Ground

Host System: KMT-2025-BLG-0121L

Spectral Class

Unknown

Effective Temperature

Estimated Age

Stellar Radius

Stellar Mass

0.610 M☉

Metallicity [Fe/H]

Distance
6,200.00 parsec
Light-years 20,221.67 ly
V-band magnitude
mag
Voyager-speed travel 356,609,166 yr

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