NGTS-20 b
NGTS-20 b is a cold gas giant orbiting the G1 IV star NGTS-20 in the constellation Eridanus. It lies about 1,249 light-years from Earth and was discovered in 2022 using the transit method.
How Big Is NGTS-20 b?
NGTS-20 b has a radius of 11.99 times that of Earth, or 1.07 times the radius of Jupiter. Its mass is 947 times that of Earth.
Is NGTS-20 b in the Habitable Zone?
NGTS-20 b orbits inside the inner edge of the habitable zone of NGTS-20. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of NGTS-20: 1.413–3.313 AU (conservative: 1.790–3.141 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on NGTS-20 b
The equilibrium temperature of NGTS-20 b is about 688 K (415 °C) — hot enough to melt many metals. 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-20 b — one full orbit around NGTS-20 — lasts 54.2 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.313 AU — closer to its star than Mercury is to the Sun. Its orbit is highly elliptical (eccentricity 0.43), swinging dramatically closer to and farther from its star.
How Was NGTS-20 b Discovered?
NGTS-20 b was discovered in 2022 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-20 b?
NGTS-20 b is 1,248.8 light-years (382.9 parsecs) from Earth. Light arriving here tonight left the planet about 1,249 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 21,978,880 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. NGTS-20 b scores 0.09, ranking #4,483 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: NGTS-20
NGTS-20
- Spectral type
- G1 IV
- Surface temperature
- 5,980 K (Sun: 5,772 K)
- Mass
- 1.47 M☉
- Radius
- 1.78 R☉
- Age
- 4.1 billion years (Sun: 4.6)
Planetary System
NGTS-20 b is the only planet known to orbit NGTS-20 so far.
NGTS-20 b — Complete Data
| Radius | 11.994 Earth radii (1.070 Jupiter radii) |
|---|---|
| Mass | 947.13 Earth masses (2.980 Jupiter masses) |
| Orbital period | 54.19 days |
| Orbital distance | 0.313 AU |
| Eccentricity | 0.432 |
| Equilibrium temperature | 688 K (415 °C) |
| Earth Similarity Index | 0.09 |
| Distance from Earth | 1,248.8 light-years (382.9 parsecs) |
| Constellation | Eridanus |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2022 |
Data: NASA Exoplanet Archive, last updated 2022-07-12. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About NGTS-20 b
Is NGTS-20 b habitable?
No — NGTS-20 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is NGTS-20 b?
NGTS-20 b is about 1,249 light-years from Earth in the constellation Eridanus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 21,978,880 years to get there.
How big is NGTS-20 b compared to Earth?
NGTS-20 b has 11.99 times the radius of Earth and about 947 times its mass.
How long is a year on NGTS-20 b?
One orbit around NGTS-20 takes 54.2 Earth days.
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