L 98-59 d
L 98-59 d is a mini-Neptune orbiting the M3 V star L 98-59 in the constellation Volans. It lies about 35 light-years from Earth and was discovered in 2019 using the transit method.
How Big Is L 98-59 d?
L 98-59 d has a radius of 1.63 times that of Earth. Its mass is 1.6 times that of Earth, giving it a density of 2.20 g/cm³ — between that of rocky and gaseous planets.
Is L 98-59 d in the Habitable Zone?
L 98-59 d orbits inside the inner edge of the habitable zone of L 98-59. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of L 98-59: 0.090–0.236 AU (conservative: 0.115–0.223 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on L 98-59 d
The equilibrium temperature of L 98-59 d is about 416 K (143 °C) — hotter than anywhere on Earth. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C. It receives 4.97 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on L 98-59 d — one full orbit around L 98-59 — lasts 7.45 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.049 AU — closer to its star than Mercury is to the Sun. Its orbit is nearly circular (eccentricity 0.006).
How Was L 98-59 d Discovered?
L 98-59 d was discovered in 2019 using the transit method, with observations from Transiting Exoplanet Survey Satellite (TESS).
The transit method watches a star for the tiny, regular dip in brightness that occurs when a planet crosses in front of it. The depth and timing of these dips reveal the planet's size and orbital period.
How Far Away Is L 98-59 d?
L 98-59 d is 34.6 light-years (10.6 parsecs) from Earth. Light arriving here tonight left the planet around the year 1992. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 608,960 years to make the journey.
Earth Similarity Index
The Earth Similarity Index (ESI) scores how physically similar a planet is to Earth, from 0 to 1, based on radius, density, escape velocity and surface temperature. L 98-59 d scores 0.53, ranking #220 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: L 98-59
L 98-59
- Spectral type
- M3 V
- Surface temperature
- 3,415 K (Sun: 5,772 K)
- Mass
- 0.29 M☉
- Radius
- 0.32 R☉
- Luminosity
- 0.0122 L☉
- Age
- 4.9 billion years (Sun: 4.6)
The L 98-59 Planetary System
L 98-59 d is one of 5 known planets in the L 98-59 system. Its siblings:
L 98-59 d — Complete Data
| Radius | 1.627 Earth radii (0.145 Jupiter radii) |
|---|---|
| Mass | 1.64 Earth masses (0.005 Jupiter masses) |
| Density | 2.20 g/cm³ (Earth: 5.51) |
| Orbital period | 7.45 days |
| Orbital distance | 0.049 AU |
| Eccentricity | 0.006 |
| Equilibrium temperature | 416 K (143 °C) |
| Stellar irradiation | 4.97× Earth |
| Earth Similarity Index | 0.53 |
| Distance from Earth | 34.6 light-years (10.6 parsecs) |
| Constellation | Volans |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2019 |
Data: NASA Exoplanet Archive, last updated 2025-07-29. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About L 98-59 d
Is L 98-59 d habitable?
No — L 98-59 d orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is L 98-59 d?
L 98-59 d is about 35 light-years from Earth in the constellation Volans. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 608,960 years to get there.
How big is L 98-59 d compared to Earth?
L 98-59 d has 1.63 times the radius of Earth and about 1.6 times its mass.
How long is a year on L 98-59 d?
One orbit around L 98-59 takes 7.5 Earth days — short enough that 49 of its years would fit into one Earth year.
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