Pleiades (M45) vs Hyades Cluster Comparison
Compare Taurus's twin naked-eye open clusters—the Pleiades (M45) and Hyades—in Gaia DR3 distance, isochrone age, stellar turnoff, and angular span.
Compared Celestial Objects
Pleiades (Messier 45 Open Cluster)
Coordinates, Gaia DR3 distance (136.2 pc), magnitude 1.6, reflection nebulosity, and observing guide for the Pleiades (M45) in Taurus.
Constellation: Taurus · Coords: 03h 47m 00.00s, +24° 07′ 00.0″
Hyades (Melotte 25 Nearest Cluster)
Coordinates, Gaia DR3 distance (47.0 pc), age 650 Myr, moving-group kinematics, and observing guide for the Hyades cluster in Taurus.
Constellation: Taurus · Coords: 04h 26m 54.00s, +15° 52′ 00.0″
Normalized Shared Parameter Table
| Parameter | Unit / Scale | Pleiades (Messier 45 Open Cluster) | Hyades (Melotte 25 Nearest Cluster) |
|---|---|---|---|
| Integrated Visual Magnitude (V) | mag | +1.60 ± 0.05 | +0.50 ± 0.05 |
| Gaia DR3 Heliocentric Distance | pc | 136.2 ± 1.2 pc (444 ly) | 47.0 ± 0.2 pc (153 ly) |
| Apparent Angular Diameter | arcmin | 110 ± 10′ (1.8°) | 330 ± 15′ (5.5°) |
| Isochrone Age | Myr | 115 ± 10 Myr | 650 ± 25 Myr |
| Iron Abundance [Fe/H] | dex | +0.01 ± 0.03 dex | +0.14 ± 0.02 dex |
Astrophysical & Observational Synthesis
Although both clusters anchor the winter constellation Taurus, the Hyades lies nearly three times closer to the Sun than the Pleiades (47.0 pc vs 136.2 pc). That proximity spreads the core of the Hyades across 5.5 degrees of sky—three times the apparent diameter of M45—making the Hyades an unmistakable naked-eye V asterism whose tidal tails stretch dozens of parsecs across the solar neighborhood.
Stellar evolution further separates the pair by more than half a billion years. At 115 Myr old, the Pleiades retains its luminous blue-white B6–B8 giants (headed by Alcyone at V = +2.87) plowing through an unrelated interstellar dust cloud that scatters blue reflection nebulosity (NGC 1432/1435). By contrast, at 650 Myr old, the Hyades main-sequence turnoff has cooled to spectral class A5–A7 (such as Theta² Tauri), and its four most massive surviving stars have swollen into K0 III orange clump giants (Gamma, Delta¹, Epsilon, and Theta¹ Tauri).
Note also a classic line-of-sight illusion in the Hyades: first-magnitude orange giant Aldebaran (Alpha Tauri, V = +0.86) sits at the tip of the Hyades V, but Gaia and Hipparcos parallaxes prove Aldebaran is an unrelated foreground star at 20.43 pc—less than half the distance of the true cluster members.
Related Reference Guides
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
- 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
- SIMBAD Astronomical Database (CDS) (2026-10 release): Wenger, M., et al. 2000, A&AS, 143, 9 (The SIMBAD astronomical database) — Centre de Données astronomiques de Strasbourg
- Revised New General Catalogue and Index Catalogue (RNGC/IC) (2024/2026 edition): Steinicke, W. 2010, Observing and Cataloguing Nebulae and Star Clusters (Cambridge Univ. Press); Verga, M. OpenNGC (CC-BY-SA 4.0 / data tables) — Wolfgang Steinicke / OpenNGC