The

Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye ...

has several smaller galaxies gravitationally bound to it, as part of the Milky Way

subgroup In group theory, a branch of mathematics, given a group ''G'' under a binary operation ∗, a subset ''H'' of ''G'' is called a subgroup of ''G'' if ''H'' also forms a group under the operation ∗. More precisely, ''H'' is a subgroup ...

, which is part of the local galaxy cluster, the

Local Group The Local Group is the galaxy group that includes the Milky Way. It has a total diameter of roughly , and a total mass of the order of . It consists of two collections of galaxies in a "dumbbell" shape: the Milky Way and its satellites form ...

. 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 Large means of great size. Large may also refer to: Mathematics * Arbitrarily large, a phrase in mathematics * Large cardinal, a property of certain transfinite numbers * Large category, a category with a proper class of objects and morphisms (or ...

and

Small Small may refer to: Science and technology * SMALL, an ALGOL-like programming language * Small (anatomy), the lumbar region of the back * ''Small'' (journal), a nano-science publication * <small>, an HTML element that defines smaller text ...

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 The Sagittarius Dwarf Spheroidal Galaxy (Sgr dSph), also known as the Sagittarius Dwarf Elliptical Galaxy (Sgr dE or Sag DEG), is an elliptical loop-shaped satellite galaxy of the Milky Way. It contains four globular clusters in ...

, 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 According to modern models of physical cosmology, a dark matter halo is a basic unit of cosmological structure. It is a hypothetical region that has decoupled from cosmic expansion and contains gravitationally bound matter. A single dark matte ...

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:

Map with clickable regions

Image:Satellite_Galaxies.svg, frame, center, Milky Way's satellite galaxies (clickable map) rect 289 219 352 251

rect 319 252 380 281

rect 187 81 229 113 Sextans Dwarf rect 168 273 249 318

Large Magellanic Cloud The Large Magellanic Cloud (LMC), or Nubecula Major, is a satellite galaxy of the Milky Way. At a distance of around 50 kiloparsecs (≈160,000 light-years), the LMC is the second- or third-closest galaxy to the Milky Way, after the ...

rect 229 326 288 368

Small Magellanic Cloud The Small Magellanic Cloud (SMC), or Nubecula Minor, is a dwarf galaxy near the Milky Way. Classified as a dwarf irregular galaxy, the SMC has a D25 isophotal diameter of about , and contains several hundred million stars. It has a total mass of ...

rect 297 376 352 407 Sculptor Dwarf rect 183 446 234 476

Fornax Dwarf The Fornax Dwarf Spheroidal (formerly known as the Fornax System) is an elliptical dwarf galaxy in the constellation Fornax that was discovered in 1938 by Harlow Shapley. He discovered it while he was in South Africa on photographic plates take ...

rect 107 297 150 332

Carina Dwarf The Carina Dwarf Spheroidal Galaxy is a dwarf galaxy in the Carina constellation. It was discovered in 1977 with the UK Schmidt Telescope The UK Schmidt Telescope (UKST) is a 1.24 metre Schmidt telescope operated by the Australian Ast ...

rect 296 107 339 144 Bootes Dwarf rect 336 180 408 196 Ursa Major II rect 357 40 423 59 Ursa Major I rect 370 110 428 142

Ursa Minor Dwarf The Ursa Minor Dwarf is a dwarf spheroidal galaxy, discovered by A.G. Wilson of the Lowell Observatory, in the United States, during the Palomar Sky Survey in 1955. It appears in the Ursa Minor constellation, and is a satellite galaxy of the Mi ...

rect 430 119 470 154 Draco Dwarf desc bottom-left

Streams

The Sagittarius Dwarf Spheroidal Galaxy is currently in the process of being consumed by the Milky Way and is expected to pass through it within the next 100 million years. The Sagittarius Stream is a stream of stars in polar orbit around the Milky Way leeched from the Sagittarius Dwarf. The

Virgo Stellar Stream The Virgo Stellar Stream, also known as Virgo Overdensity, is the proposed name for a stellar stream in the constellation of Virgo which was discovered in 2005. The stream is thought to be the remains of a dwarf spheroidal galaxy that is in the p ...

is a stream of stars that is believed to have once been an orbiting dwarf galaxy that has been completely distended by the Milky Way's gravity.

Characteristics

List

Map with clickable regions

Streams

See also

Notes

References

Further reading