Andromeda Galaxy
M 31
Scientific overview
Andromeda Galaxy is a spiral galaxy in the constellation Andromeda. It shines at apparent magnitude 3.44 and spans about 177.83 arcminutes of sky.
Observation guide
Guidance follows standard observing practice, derived from the object's real magnitude and position. A dark, moonless sky always helps.
Location in the sky
Precision measurements
Distances and velocities from SIMBAD and redshift from NED · M 31
| Distance | 2,482,050 ly | SIMBAD · catalogued |
| Physical size (major axis) | 128,393 ly | SIMBAD · derived |
| Physical size (minor axis) | 50,294 ly | SIMBAD · derived |
| Redshift (z) | -0.000991 ± 3.0000e-6 | NED · catalogued |
| Radial velocity | -300 ± 4 km/s | SIMBAD · measured |
| Right ascension (ICRS) | 10.684708 deg | SIMBAD · measured |
| Declination (ICRS) | 41.26875 deg | SIMBAD · measured |
Full field-level provenance
- Distance: Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · mesDistance · dist · 2021ApJ...920...84L · catalogued value · source value 761 kpc · retrieved 2026-07-11
- Physical size (major axis): Centre de données astronomiques de Strasbourg (CDS) · derived (OpenNGC angular size × SIMBAD distance) · physical size = angular size × distance (small-angle); angular size from OpenNGC, distance from SIMBAD mesDistance · derived · retrieved 2026-07-11
- Physical size (minor axis): Centre de données astronomiques de Strasbourg (CDS) · derived (OpenNGC angular size × SIMBAD distance) · physical size = angular size × distance (small-angle); angular size from OpenNGC, distance from SIMBAD mesDistance · derived · retrieved 2026-07-11
- Redshift (z): NASA/IPAC Extragalactic Database · NED · ObjectLookup · Redshift · 2000UZC...C......0F · catalogued value · NED quality SUN · retrieved 2026-07-11
- Radial velocity: Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · rvz_radvel · 2012AJ....144....4M · direct catalogue measurement · retrieved 2026-07-11
- Right ascension (ICRS): Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · ra · 2006AJ....131.1163S · direct catalogue measurement · retrieved 2026-07-11
- Declination (ICRS): Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · dec · 2006AJ....131.1163S · direct catalogue measurement · retrieved 2026-07-11
Physical size is derived from the OpenNGC angular size and the catalogued distance (small-angle: size = angle × distance). Redshift is the object's measured redshift — a negative value is a blueshift (the galaxy is approaching, its motion dominated by local rather than cosmic expansion). Fields a source did not provide are omitted, never invented.
Other objects in Andromeda
| Object | Type | Mag | Size (′) |
|---|---|---|---|
| NGC 7686NGC 7686 | Open cluster | 5.6 | 3.6 |
| NGC 752C 28 · NGC 752 | Open cluster | 5.7 | 39 |
| M 32M 32 · NGC 221 | Elliptical galaxy | 8.13 | 7.74 |
| M 110M 110 · NGC 205 | Elliptical galaxy | 8.15 | 16.22 |
| Copeland's Blue SnowballC 22 · NGC 7662 | Planetary nebula | 8.3 | 0.28 |
| NGC 956NGC 956 | Open cluster | 8.9 | 4.5 |
| NGC 891C 23 · NGC 891 | Spiral galaxy | 10.01 | 13.03 |
Sources
The primary and reference sources this topic draws on.
- OpenNGCOpenNGC (M. Verga) — NGC/IC, Messier, and Caldwell catalogue data
Openly-licensed deep-sky catalogue: object types, positions, magnitudes, sizes, morphology, and cross-identifiers.