OVERVIEW
] GALAXYAndromeda Galaxy is a spiral galaxy Sb in the constellation Andromeda, 2.537 from Earth, shining at apparent magnitude 3.44 (). Other catalogues list it as 2MASX J00424433+4116074, HD 3969 and IRAS 00400+4059, among 11 designations in total. It was first recorded in the year 964.
Our nearest large galactic neighbor, a trillion stars on a slow collision course with the Milky Way. Merger scheduled in four billion years.
- WHAT IT IS
- Spiral galaxy
- HOW FAR
- 2.537
- HOW BIG ON THE SKY
- 2.96
- HOW BRIGHT (V)
The light arriving now left it that long ago.
About 5.7 full Moons wide.
Bright enough for the naked eye, under a sky dark enough.
THE MODEL
] LIGHT ALONG THE RAYCALCULATED · NOT AN OBSERVATION · ANGULAR SIZE AT THE CATALOGUED DISTANCE · HUBBLE TYPE Sb · SURFACE BRIGHTNESS 23.6 MAG/ARCSEC² · MAJOR AXIS 178′ · AXIS RATIO 0.39 · POSITION ANGLE 35° · NO SURFACE — DRAWN AS A VOLUME · AXIS RATIO READ AS AN INCLINATION
An exponential disc with a bulge at the middle and arms wound at the pitch angle its Hubble type implies, with the dust drawn where the dust is: on the inner edge of each arm, ahead of the crest, because inside co-rotation the gas overtakes the spiral pattern and piles up as it goes in. The shape of it is the catalogued morphology; the tilt is the catalogued axis ratio read as an inclination, which is what a round disc's axis ratio is. Nothing measured the depth — a disc that looks this elliptical from the Sun is this far over, and the model is that disc seen from wherever you turn it to. The two colours are two populations: old stars in the bulge and the disc, young ones in the arms, both through the same blackbody table as the star pages. Drag it, or use the arrow keys, to look from another direction. The stars behind are the 498,631 this catalogue holds real distances for, drawn from where the camera actually is — but every one of them is within 170 parsecs of the Sun and this object is much further out, so from here that whole neighbourhood is a knot in one direction and the rest of the sky is empty. The view you land on looks the other way; turn back towards the Sun and the stars come with it. What the readout says is which of the two the frame is pointed at. The emptiness is not a missing backdrop — it is the edge of what this catalogue has measured.
IMAGES
] 3 FRAMES- Brody Wesner
CC0 - Lviatour
CC BY-SA 2.5 - David (Deddy) Dayag
CC BY-SA 4.0
OBSERVING
] FROM WHERE YOU AREWhat it takes to see Andromeda Galaxy for yourself. Everything in this part of the page is worked out for a real horizon, a real night and the equipment you say you have.
Say where you are, and this line says when Andromeda Galaxy is worth going out for.
THROUGH AN EYEPIECE
] 150 MM TELESCOPE · 25 MM EYEPIECEBright enough to see with your eyes alone, once you are away from town lights. Andromeda Galaxy covers 2.96° of sky against a of 1.08°, so at 48× it is wider than the field — sweep across it.
- 48×
- 1.08
- 1.25
- 13.0
- SIZE ON THE SKY
- 2.96
- FILLS OF THE FIELD
- more than 100% of the width
- APPARENT MAGNITUDE ()
- 3.44 · within reach
Andromeda Galaxy is not a point of light, so the limit above is the wrong one to hold it against: the same brightness spread over 2.96° of sky is harder than a star of it, and goes first — spread out, it comes to 23.6 . Catalogued sizes are measured to a photographic contour, and the part an eye sees is usually smaller.
APPARENT PLACE
] EQUINOX J2026.7Where a telescope has to be pointed today, which is not quite where the catalogue records the object: the coordinate grid itself has turned since the year 2000 the catalogue is referred to.
- RIGHT ASCENSION
- DECLINATION
- GRID TURNED SINCE
- 18.7
- PROPER MOTION SINCE
- none published
Computed for 2026-09-07 00:00 UT. No proper motion is published for Andromeda Galaxy, so nothing here moves the object; what separates this from the catalogued position above is the coordinate grid turning under it — about fifty arcseconds a year of precession since 2000, and the small nodding of the Earth’s axis on top of that. Aberration and refraction are not included, and neither is parallax; each is under an arcminute, which is also about as well as the catalogued position is known. The same figure for any date.
CATALOG DATA
] 17 FIELDSThe raw catalogue values, as the source published them, with the error bars where one was published — sorted by what each set of figures is about rather than by the order they happened to be stored in.
WHAT KIND OF THING IT IS
What the object is in itself, rather than how it happens to look from here.
- Hubble type
HOW BRIGHT IT IS
What the light adds up to, measured through one filter at a time. A magnitude is a brightness on a backwards scale — the smaller the number, the brighter the object.
- Apparent magnitude ()
- Apparent magnitude ()
- Apparent magnitude ()
- Apparent magnitude ( band)
- Apparent magnitude ()
- Surface brightness
- 23.63
WHERE IT IS AND HOW IT MOVES
Position, motion across the sky and the size it covers on it. These are measurements of the object as seen from here, so every one of them depends on where here is.
- −300
- Redshift (z)
- Redshift (z, CMB frame)
- Major axis
- 177.83
- Minor axis
- 69.66
- 35
OTHER NAMES AND NUMBERS
The identifiers other catalogues file this object under, for anyone joining this data to theirs.
- Also known as
- Andromeda, Andromeda Nebula
- OpenNGC type code
- G
- Wikidata item
- Q2469
- Wikipedia article
- Andromeda Galaxy
ALSO KNOWN AS
] 11 DESIGNATIONS- 2MASX 2MASX J00424433+4116074
- Common name Andromeda Galaxy
- HD HD 3969
- IRAS IRAS 00400+4059
- IRAS IRAS F00400+4059
- LEDA LEDA 2557
- MCG MCG +07-02-016
- Messier M 31
- NGC NGC 224
- PGC PGC 2557
- UGC UGC 454
LOOK IT UP ELSEWHERE
] 4 SERVICESEach link carries the identifier printed beside it. Nothing on this page is a measurement of our own, so a number that disagrees with one of these is worth reporting — and a service that has never catalogued this object under this name will say so plainly.
- SIMBADM 31
Cross-identifications, measured values and the reference behind each of them.
- NEDM 31
Redshift-independent distances, photometry across the spectrum and the extragalactic literature.
- ADSobject:"M 31"
Papers indexed against this object rather than against the string, newest first.
- VizieR600″ around 10.6848 +41.2691
Every published table with a row at this position, searched by coordinates rather than by name.
CITE THIS PAGE
] DR1This page is live and its numbers move when an upstream refreshes, so the citation names the release the rows belong to rather than the day you read them. The release itself is frozen, republished as a bundle, and is what a data-availability statement should point at.
SpaceCatalog. Andromeda Galaxy [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/m31
@misc{spacecatalog_m31,
author = {{SpaceCatalog}},
title = {{Andromeda Galaxy}},
howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},
year = {2026},
url = {https://spacecatalog.org/object/m31},
note = {Catalogue entry, data release DR1 (2026-08-21). Values from OpenNGC.}
}The values above were taken from OpenNGC — CC-BY-SA-4.0. Citing this page does not replace citing that catalogue, and its licence is share-alike: the terms reach whatever you build from these rows.
RECENT ACTIVITY
] 3 ITEMS- AT 2025abao: The fourth luminous red nova in M 312026-02-14 · arXiv · PAPER · A. Reguitti, A. Pastorello, G. Valerin, F. D. Romanov, A. Siviero, Y. -Z. Cai
- Accounting for the absence of anomalous microwave emission in the M 31 halo2025-10-16 · arXiv · PAPER · Francesco De Paolis, Faryal Naseem, Noraiz Tahir
- SDSO1 is a Shocked Ghost Planetary Nebula in Front of M 312025-07-21 · arXiv · PAPER · Patrick Ogle, Mark Petersen, R. Michael Rich, Tim Schaeffer, Lewis McCallum, Alberto Noriega-Crespo
arXiv · UPDATED DAILY