The ten largest known galaxies by diameter, from the immense IC 1101 down to the Triangulum Galaxy.
Quick answer: 1. IC 1101, 2. Malin 1, 3. UGC 2885, 4. Hercules A (3C 348), 5. NGC 262 (Mrk 348), 6. NGC 4889 (Coma B), 7. Centaurus A (NGC 5128), 8. Andromeda Galaxy (M31), 9. Milky Way, 10. Triangulum Galaxy (M33).
Galaxies are vast collections of stars, gas, dust, and dark matter held together by gravity. This list ranks the ten largest known galaxies by their estimated diameters, spanning giant ellipticals, lenticular galaxies, and massive spirals. It's a reference for astronomy enthusiasts, students, and anyone curious about the sheer scale of the universe. The ranking runs from largest to smallest, so rank 1 is the galaxy with the greatest diameter.
The largest known galaxy, a supergiant elliptical at the center of the Abell 2029 galaxy cluster roughly 1.04 billion light-years from Earth. Its extended halo spans an estimated 5.5 million light-years — more than 50 times the diameter of the Milky Way.
A giant low-surface-brightness spiral galaxy discovered in 1986 by astronomer David Malin. Its vast, faint disk spans about 650,000 light-years, making it one of the largest spiral galaxies known.
Known as the 'Rubin Galaxy' after astronomer Vera Rubin, this giant spiral galaxy in Perseus spans about 463,000 light-years. It is one of the largest known spiral galaxies and contains an estimated 1 trillion stars.
A giant elliptical galaxy at the center of a powerful radio source. Its visible stellar halo spans about 450,000 light-years, and its radio jets extend far beyond the galaxy into the intergalactic medium.
A large lenticular galaxy with a faint, extended disk of neutral hydrogen that reaches about 360,000 light-years in diameter. It is one of the most massive galaxies in the Perseus-Pisces supercluster.
A supergiant elliptical galaxy at the center of the Coma Cluster, one of the richest galaxy clusters in the nearby universe. Its halo spans about 330,000 light-years and once hosted one of the largest black holes ever found.
The nearest giant elliptical and one of the brightest radio sources in the sky. Its warped dust lane and enormous radio lobes suggest a past merger with a spiral galaxy, and its visible halo spans about 300,000 light-years.
The largest galaxy in the Local Group and the nearest major galaxy to the Milky Way. It is approaching the Milky Way and will merge with it in about 4.5 billion years. Its disk spans roughly 220,000 light-years.
Our home galaxy, a barred spiral that contains an estimated 100–400 billion stars including the Sun. Its diameter is about 100,000 light-years, though recent studies suggest the outer disk may extend up to 200,000 light-years.
The third-largest member of the Local Group after Andromeda and the Milky Way. It is a small, unbarred spiral galaxy and a satellite of the Andromeda Galaxy, spanning about 60,000 light-years.
| # | Name | type | constellation | distance |
|---|---|---|---|---|
| 1 | IC 1101 | Supergiant elliptical (cD) | Virgo | 1.04 billion ly |
| 2 | Malin 1 | Low-surface-brightness spiral | Coma Berenices | 1.2 billion ly |
| 3 | UGC 2885 | Spiral (SAc) | Perseus | 313 million ly |
| 4 | Hercules A (3C 348) | Giant elliptical (radio galaxy) | Hercules | 2.1 billion ly |
| 5 | NGC 262 (Mrk 348) | Lenticular (S0) | Andromeda | 287 million ly |
| 6 | NGC 4889 (Coma B) | Supergiant elliptical (cD) | Coma Berenices | 308 million ly |
| 7 | Centaurus A (NGC 5128) | Peculiar elliptical (radio galaxy) | Centaurus | 13.1 million ly |
| 8 | Andromeda Galaxy (M31) | Barred spiral (Sb) | Andromeda | 2.54 million ly |
| 9 | Milky Way | Barred spiral (SBbc) | Sagittarius (center) | 0 (home galaxy) |
| 10 | Triangulum Galaxy (M33) | Unbarred spiral (Sc) | Triangulum | 3.0 million ly |
Galaxies are ranked by estimated diameter in light-years, using figures from published astronomical surveys and NASA/IPAC Extragalactic Database (NED) data as compiled in Wikipedia's "List of largest galaxies." Diameters are based on the galaxy's visible extent (isophotal diameter at the B-band 25 mag/arcsec² level for most entries). For giant ellipticals like IC 1101, the diameter includes the extended halo. The ranking runs from largest to smallest.
IC 1101 is the largest known galaxy, a supergiant elliptical at the center of the Abell 2029 cluster. Its extended halo spans about 5.5 million light-years in diameter — more than 50 times the size of the Milky Way.
The Milky Way is about 100,000 light-years in diameter, making it average-sized among large galaxies. It is about 55 times smaller than IC 1101 and less than half the diameter of the Andromeda Galaxy.
Yes. Theoretical models suggest that galaxy growth is limited by the availability of gas and dark matter in its environment, as well as feedback from supermassive black holes. The largest galaxies, called cD or giant ellipticals, are found at the centers of galaxy clusters.
No, but the very largest galaxies tend to be giant ellipticals (cD galaxies). Large spiral galaxies exist — such as UGC 2885, Malin 1, and Andromeda — but they rarely exceed about 500,000 light-years before becoming unstable.