Confirmed Exoplanet Discovered 2025

KMT-2024-BLG-1281L b

A neptune-like orbiting the unknown KMT-2024-BLG-1281L, located approximately 23,418.0 light-years from Earth.

Key parameters at a glance

  • A radius of 4.59 Earth radii
  • A mass of 19.07 Earth masses
  • Surface gravity around 0.91 g
  • Semi-major axis 1.9600 AU
  • Distance from Earth 23,418.00 light-years
  • Earth Similarity Index 0.501
  • Travel time at Voyager 1 speed 412,976,421 years

KMT-2024-BLG-1281L b Planet Profile

Physical Specs

Radius
4.59 R⊕
Radius (Jupiter)
0.409 R♃
Mass
19.07 M⊕
Mass (Jupiter)
0.060 M♃
Density
1.08 g/cm³
Surface Gravity
0.91 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.501
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

#449of 574

top 78.0%

This planet

4.59R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

Metric Earth KMT-2024-BLG-1281L b Jupiter
Radius (R⊕)1.004.5911.21
Mass (M⊕)1.0019.07317.83
Density (g/cm³)5.511.081.33
Surface Gravity (g)1.000.912.53
Insolation (S⊕)1.000.037

Alternative Mass Estimates

Method Value Interpretation
Best measured mass 19.070 M⊕ Direct mass measurement (not derived).

Percentile among Neptune-like cohort

Radius 4.590 R⊕ · percentile 21 / cohort 574
Mass 19.070 M⊕ · percentile 25 / cohort 574
Distance 7,180.00 pc · percentile 97 / cohort 572
ESI 0.501 · percentile 90 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period
days
Semi-major axis
1.9600 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)

0.501

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Han et al. 2025

Instrument

18k Mosaic CCD camera

Publication

2025-10

Observation locale

Ground

Host System: KMT-2024-BLG-1281L

Spectral Class

Unknown

Effective Temperature

Estimated Age

Stellar Radius

Stellar Mass

0.320 M☉

Metallicity [Fe/H]

Distance
7,180.00 parsec
Light-years 23,418.00 ly
V-band magnitude
mag
Voyager-speed travel 412,976,421 yr

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