TRAPPIST-1 e vs Proxima Centauri b Comparison
Compare the two benchmark temperate M-dwarf rocky exoplanets TRAPPIST-1 e and Proxima Centauri b: detection method, mass, radius, and habitability.
Compared Celestial Objects
TRAPPIST-1 e (Temperate Terrestrial World)
Coordinates, Gaia distance (12.47 pc), 6.10-day orbital period, mass 0.692 M⊕, radius 0.920 R⊕, and JWST transit spectroscopy for TRAPPIST-1 e.
Constellation: Aquarius · Coords: 23h 06m 29.28s, -05° 02′ 28.6″
Proxima Centauri b (Nearest Exoplanet)
Coordinates, ESPRESSO minimum mass (1.07 M⊕), 11.186-day habitable-zone orbit at 0.04856 AU, and stellar flare environment of Proxima Centauri b.
Constellation: Centaurus · Coords: 14h 29m 42.95s, -62° 40′ 46.1″
Normalized Shared Parameter Table
| Parameter | Unit / Scale | TRAPPIST-1 e (Temperate Terrestrial World) | Proxima Centauri b (Nearest Exoplanet) |
|---|---|---|---|
| Heliocentric Distance | pc | 12.467 ± 0.012 pc (40.66 ly) | 1.3020 ± 0.0003 pc (4.246 ly) |
| Planetary Mass | M⊕ | 0.692 ± 0.022 M⊕ (true mass) | 1.07 ± 0.06 M⊕ (minimum M sin i) |
| Planetary Radius | R⊕ | 0.920 ± 0.013 R⊕ (transiting) | Unmeasured (non-transiting) |
| Orbital Period | days | 6.09957 ± 0.00001 days | 11.1868 +0.0029/−0.0031 days |
| Equilibrium Temperature (Teq) | K | 251.3 ± 4.9 K | 234 ± 14 K |
Astrophysical & Observational Synthesis
Proxima Centauri b sits nearly ten times closer to Earth than TRAPPIST-1 e (1.30 pc vs 12.47 pc), making it our nearest extrasolar neighbor. However, because Proxima b's orbital plane is inclined away from our line of sight, it does not transit its star: radial-velocity measurements yield only a minimum mass (M sin i = 1.07 M⊕) while leaving its physical radius and bulk density unconstrained.
Conversely, TRAPPIST-1 e transits its ultracool M8 V host star every 6.10 days within a resonant seven-planet chain. Combining transit depths with resonant transit-timing variations (TTVs) pins down both its exact radius (0.920 R⊕) and true mass (0.692 M⊕), proving an Earth-like rocky-iron bulk density and enabling JWST transmission spectroscopy.
Related Reference Guides
Exoplanet Transit & Radial Velocity Methods
How astronomers detect and characterize exoplanets using photometric transit depth ((Rp/R*)²), Doppler radial velocity (M sin i), and JWST transmission spectra.
Trigonometric Parallax, Parsecs & Gaia DR3
How trigonometric parallax (d_pc = 1 / p_arcsec), the distance modulus equation, Hipparcos, and Gaia DR3 microarcsecond astrometry measure cosmic distances.
Stellar Spectral Classification (OBAFGKM)
Reference guide to Morgan-Keenan (MK) stellar classification (O B A F G K M), luminosity classes (I–V, WD), color index (B-V), and the H-R diagram.
Primary Catalogs & Scientific Sources
- NASA Exoplanet Archive (2026-10-01 snapshot): Akeson, R. L., et al. 2013, PASP, 125, 989; NASA Exoplanet Archive (IPAC/Caltech) — NASA Exoplanet Science Institute (NExScI / Caltech / IPAC)
- ESA Gaia Archive — Data Release 3 (DR3 (2022-06-13)): Gaia Collaboration, Vallenari, A., et al. 2023, A&A, 674, A1 (Gaia Data Release 3) — European Space Agency / Gaia DPAC