Satellite galaxies of the Milky Way
The Milky Way has several smaller galaxies gravitationally bound to it, as part of the Milky Way subgroup, which is part of the local galaxy cluster, the Local Group.
There are 59 small galaxies confirmed to be within of the Milky Way, but not all of them are necessarily in orbit, and some may themselves be in orbit of other satellite galaxies. The only ones visible to the naked eye are the Large and Small Magellanic Clouds, which have been observed since prehistory. Measurements with the Hubble Space Telescope in 2006 suggest the Magellanic Clouds may be moving too fast to be orbiting the Milky Way. Of the galaxies confirmed to be in orbit, the largest is the Sagittarius Dwarf Elliptical Galaxy, which has a diameter of or roughly a twentieth that of the Milky Way.
Characteristics
Satellite galaxies that orbit from of the edge of the disc of the Milky Way Galaxy to the edge of the dark matter halo of the Milky Way at from the center of the galaxy, are generally depleted in hydrogen gas compared to those that orbit more distantly. This is because of their interactions with the dense hot gas halo of the Milky Way that strip cold gas from the satellites. Satellites beyond that region still retain copious quantities of gas.List
The Milky Way's satellite galaxies include the following:| Name | Diameter | Distance | Absolute visual magnitude | Type | Discovered |
| Large Magellanic Cloud | 4 | 48.5 | −18.1 | SBm | prehistoric |
| Antlia II | 2.9 | 130 | −8.5 | ? | 2018 |
| Sagittarius Dwarf | 2.6 | 20 | −13.5 | E | 1994 |
| Crater II | 2.2 | 117.5 | −8.2 | dSph | 2016 |
| Small Magellanic Cloud | 2 | 61 | −16.8 | Irr | prehistoric |
| Canes Venatici I | 2 | 220 | −8.6 | dSph | 2006 |
| Canis Major Dwarf | 1.5 | 8 | - | Irr | 2003 |
| Boötes III | 1.0 | 46 | −5.75 | dSph? | 2009 |
| Sculptor Dwarf | 0.8 | 90 | −11.1 | dE3 | 1937 |
| Draco Dwarf | 0.7 | 80 | −8.8 | dE0 | 1954 |
| Hercules | 0.7 | 135 | −6.6 | dSph | 2006 |
| Leo II | 0.7 | 210 | −9.8 | dE0 | 1950 |
| Fornax Dwarf | 0.6 | 140 | −13.4 | dE2 | 1938 |
| Eridanus II | 0.55 | 366 | −7.1 | dSph | 2015 |
| Sextans Dwarf Spheroidal | 0.5 | 90 | −9.3 | dE3 | 1990 |
| Carina Dwarf Spheroidal | 0.5 | 100 | −9.1 | dE3 | 1977 |
| Leo I | 0.5 | 250 | −12.0 | dE3 | 1950 |
| Ursa Minor Dwarf | 0.4 | 60 | −8.8 | dE4 | 1954 |
| Leo T | 0.34 | 420 | −8.0 | dSph/dIrr | 2006 |
| Aquarius II | 0.32 | 108 | −4.2 | dSph | 2016 |
| Boötes I | 0.30 | 60 | −6.3 | dSph | 2006 |
| Canes Venatici II | 0.30 | 155 | −4.9 | dSph | 2006 |
| Leo IV | 0.30 | 160 | −5.8 | dSph | 2006 |
| Tucana IV | 0.25 | 48 | −3.5 | dSph | 2015 |
| Columba I | 0.21 | 182 | −4.5 | dSph | 2015 |
| Ursa Major II Dwarf | 0.20 | 30 | −4.25 | dG D | 2006 |
| Grus II | 0.19 | 53 | −3.9 | dSph | 2015 |
| Cetus III | 0.18 | 251 | −2.4 | dSph? | 2017 |
| Coma Berenices | 0.14 | 42 | −4.1 | dSph | 2006 |
| Hydra II | 0.14 | 128 | −4.8 | dSph | 2015 |
| Reticulum III | 0.13 | 92 | −3.3 | dSph | 2015 |
| Pisces II | 0.12 | 180 | −5.0 | dSph | 2010 |
| Pegasus III | 0.11 | 215 | −3.4 | dSph | 2015 |
| Hydrus I | 0.10 | 28 | −4.7 | dSph | 2018 |
| Boötes II | 0.10 | 42 | −2.7 | dSph | 2007 |
| Tucana III | 0.09 | 25 | −2.4 | dSph | 2015 |
| Virgo | 0.09 | 91 | −0.3 | dSph? | 2016 |
| Horologium II | 0.09 | 78 | −2.6 | dSph | 2015 |
| Sagittarius II | 0.08 | 67 | −5.2 | dSph | 2015 |
| Leo V | 0.08 | 180 | −5.2 | dSph | 2007 |
| Triangulum II | 0.07 | 30 | −1.8 | dSph | 2015 |
| Segue 2 | 0.07 | 35 | −2.5 | dSph | 2007 |
| Segue 1 | 0.06 | 23 | −1.5 | dSph | 2007 |
| Draco II | 0.04 | 20 | −2.9 | dSph | 2015 |
| Tucana V | 0.03 | 55 | −1.6 | dSph | 2015 |
| Cetus II | 0.03 | 30 | 0.0 | dSph? | 2015 |
| Reticulum II | - | 30 | −3.6 | dSph | 2015 |
| Tucana II | - | 70 | −3.9 | dSph | 2015 |
| Pisces I | - | 80 | - | dSph? | 2009 |
| DES 1 | - | 82 | - | GC | 2016 |
| Eridanus III | - | 90 | −2.4 | dSph? | 2015 |
| Horologium I | - | 100 | −3.5 | dSph? | 2015 |
| Kim 2/Indus I | - | 100 | - | GC | 2015 |
| Phoenix II | - | 100 | −3.7 | dSph? | 2015 |
| Ursa Major I Dwarf | - | 100 | −5.5 | dG D | 2005 |
| Pictoris I | - | 115 | −3.7 | dSph? | 2015 |
| Grus I | - | 120 | −3.4 | dSph | 2015 |
| Carina II | 0.182 | 36 | −4.5 | dSph | 2018 |
| Carina III | 0.06 | 28 | −2.4 | GC? | 2018 |
| Boötes IV | 0.28 | 209 | −4.53 | - | 2019 |
| Centaurus I | 0.076 | 116 | −5.55 | - | 2020 |
| Laevens 1 | 20 | 145 | −4.8 | - | 2018 |
| Pictor II | 0.046 | 46 | −3.2 | - | 2016 |
| Willman 1 | 0.02 | 38 | −2.53 | - | 2018 |