Andromeda (M31) vs Messier 87 Galaxy Comparison
Compare Local Group spiral Andromeda (M31) against Virgo Cluster cD giant elliptical Messier 87 in virial mass, black hole scale, and morphology.
Compared Celestial Objects
Andromeda Galaxy (Messier 31 / NGC 224)
Coordinates, Cepheid/TRGB distance (765 kpc / 2.50 Mly), magnitude 3.44, blueshift (−300 km/s), and observing guide for Andromeda (M31).
Constellation: Andromeda · Coords: 00h 42m 44.33s, +41° 16′ 07.5″
Messier 87 (Virgo A Giant Elliptical Galaxy)
Coordinates, distance (16.4 Mpc / 53.5 Mly), EHT 6.5-billion M☉ black hole M87*, relativistic jet, and observing guide for Messier 87.
Constellation: Virgo · Coords: 12h 30m 49.42s, +12° 23′ 28.0″
Normalized Shared Parameter Table
| Parameter | Unit / Scale | Andromeda Galaxy (Messier 31 / NGC 224) | Messier 87 (Virgo A Giant Elliptical Galaxy) |
|---|---|---|---|
| Integrated Visual Magnitude (V) | mag | +3.44 ± 0.05 | +8.63 ± 0.06 |
| Heliocentric Distance | Mpc | 0.778 ± 0.019 Mpc (2.54 Mly) | 16.8 ± 0.7 Mpc (54.8 Mly) |
| Apparent Major Diameter | arcmin | 178 ± 10′ (3.0°) | 8.3 ± 0.5′ |
| Total Virial Halo Mass | M☉ | (1.5 ± 0.3) × 10¹² M☉ | (6.5 ± 1.5) × 10¹³ M☉ |
| Supermassive Black Hole Mass | M☉ | (1.4 ± 0.4) × 10⁸ M☉ | (6.5 ± 0.7) × 10⁹ M☉ (M87*) |
Astrophysical & Observational Synthesis
Although the Andromeda Galaxy (M31) spans 3 degrees on our autumn sky and outshines Messier 87 by more than 5.1 magnitudes in apparent light (+3.44 vs +8.63), that apparent dominance is purely an effect of M31 sitting 21.6 times closer to the Milky Way (0.778 Mpc vs 16.8 Mpc). In intrinsic luminosity and total mass, M87 dwarfs M31 by more than an order of magnitude.
Sitting at the bottom of the Virgo Cluster's gravitational potential well, M87 (Virgo A) is a pressure-supported cD supergiant elliptical enclosing ~6.5 × 10¹³ M☉ of dark matter, hot X-ray gas, and stars within its outer halo, surrounded by ~12,000–15,000 globular clusters (compared to ~460 in M31). Its central black hole, M87*, weighs 6.5 billion solar masses (~46× M31's central black hole) and launches a 1.5-kiloparsec relativistic plasma jet.
M31, by contrast, is a rotationally supported SA(s)b spiral galaxy with cold H I gas, dark dust lanes, OB star-forming rings, and two prominent dwarf elliptical satellites (M32 and M110)—providing a mirror of what the Milky Way–Andromeda merger will eventually transform into when it forms 'Milkomeda' several billion years from now.
Related Reference Guides
Apparent vs Absolute Magnitude Explained
Understand the logarithmic Pogson astronomical magnitude scale, apparent visual magnitude (m), absolute magnitude (M at 10 parsecs), and bolometric corrections.
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.
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