Sombrero Galaxy vs Whirlpool Galaxy
Similar magnitudes, different propositions. The Sombrero (M104, NGC 4594) records 8.59 and the Whirlpool (M51, NGC 5194) 8.36, a difference too small to matter at the eyepiece. Extent is what separates them: M51 spreads across 13.71 arcminutes against 8.45 for M104, so the Sombrero concentrates its light to about 13.0 magnitudes per square arcminute where the Whirlpool falls to 13.8. The edge-on Sombrero consequently holds together under mediocre skies as a bright spindle bisected by its dust lane, while M51's face-on spiral arms demand darkness and aperture before they emerge from the background.
Property comparison
| Property | Sombrero Galaxy | Whirlpool Galaxy |
|---|---|---|
| Object type | Galaxy | Galaxy |
| Catalogue designation | NGC 4594 | NGC 5194 |
| Integrated magnitude | 8.59 | 8.36 |
| Apparent size | 8.4′ (8.45′) | 14′ (13.71′) |
| Mean surface brightness | 13.0 mag/arcmin² | 13.8 mag/arcmin² |
| Position (J2000) | RA 12h, Dec -11° | RA 13h, Dec +47° |
| Sky region | Southern sky | Far northern sky |
Mean surface brightness is derived from the integrated magnitude and the apparent diameter; higher values mean a fainter, more diffuse surface.
Full data for each object: Sombrero Galaxy · Whirlpool Galaxy
Key differences
Key Differences
- ◆ Magnitudes are close: 8.36 for M51 against 8.59 for M104.
- ◆ M51 spans 13.71 arcminutes against 8.45 for M104, about 1.6 times wider.
- ◆ M104 has the higher surface brightness, near 13.0 magnitudes per square arcminute against 13.8.
- ◆ M104 lies at declination −11°, M51 at +47° — nearly 60 degrees apart in the sky.
- ◆ M104 presents edge-on with a dust lane; M51 presents face-on with its companion NGC 5195.