NGTS-39 b
NGTS-39 b is a cold gas giant orbiting the F9 V star NGTS-39 in the constellation Canis Minor. It lies about 908 light-years from Earth and was discovered in 2026 using the transit method.
How Big Is NGTS-39 b?
NGTS-39 b has a radius of 12.20 times that of Earth, or 1.09 times the radius of Jupiter. Its mass is 466 times that of Earth, giving it a density of 1.41 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is NGTS-39 b in the Habitable Zone?
NGTS-39 b orbits inside the inner edge of the habitable zone of NGTS-39. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of NGTS-39: 0.940–2.199 AU (conservative: 1.190–2.085 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on NGTS-39 b
The equilibrium temperature of NGTS-39 b is about 519 K (246 °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.
Orbit and Year Length
A year on NGTS-39 b — one full orbit around NGTS-39 — lasts 58.2 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.308 AU — closer to its star than Mercury is to the Sun. Its orbit is highly elliptical (eccentricity 0.39), swinging dramatically closer to and farther from its star.
How Was NGTS-39 b Discovered?
NGTS-39 b was discovered in 2026 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 NGTS-39 b?
NGTS-39 b is 908.0 light-years (278.4 parsecs) from Earth. Light arriving here tonight left the planet around the year 1118. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 15,980,800 years to make the journey.
The Host Star: NGTS-39
NGTS-39
- Spectral type
- F9 V
- Surface temperature
- 6,053 K (Sun: 5,772 K)
- Mass
- 1.16 M☉
- Radius
- 1.16 R☉
- Age
- 2.2 billion years (Sun: 4.6)
Planetary System
NGTS-39 b is the only planet known to orbit NGTS-39 so far.
NGTS-39 b — Complete Data
| Radius | 12.195 Earth radii (1.088 Jupiter radii) |
|---|---|
| Mass | 466.25 Earth masses (1.467 Jupiter masses) |
| Density | 1.41 g/cm³ (Earth: 5.51) |
| Orbital period | 58.20 days |
| Orbital distance | 0.308 AU |
| Eccentricity | 0.386 |
| Equilibrium temperature | 519 K (246 °C) |
| Distance from Earth | 908.0 light-years (278.4 parsecs) |
| Constellation | Canis Minor |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2026 |
Data: NASA Exoplanet Archive, last updated 2026-07-30. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About NGTS-39 b
Is NGTS-39 b habitable?
No — NGTS-39 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is NGTS-39 b?
NGTS-39 b is about 908 light-years from Earth in the constellation Canis Minor. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 15,980,800 years to get there.
How big is NGTS-39 b compared to Earth?
NGTS-39 b has 12.20 times the radius of Earth and about 466 times its mass.
How long is a year on NGTS-39 b?
One orbit around NGTS-39 takes 58.2 Earth days.
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