Mutter's Spiral
The Time Lord designation for the galaxy in which the Sol system is located. Humans know Mutter's Spiral as the Milky Way or as Adric referred to it, Galaxia Kyklos.
Planets and other locales located within Mutter's Spiral
The following planets have either been visited by the Doctor and/or his companions, or have been mentioned in the various Doctor Who stories. They are either definitely located within Mutter's Spiral, or may be inferred to be:
The Sol System
Cassius; Earth; Fendhal homeworld; Iapetus; Jupiter; Mars; Mondas; the Moon; Neptune; Pluto; Titan; Venus; Victoria; Voga; Vulcan
Other planetary systems
Alpha Centauri; Arcturus; Argolis; Avalon; Azure; Bukol; Cait; Capella; Calderon IV; Calufrax; Chameleon homeworld; Daemos; Darkheart; Delta Magna; Deva Loka; Dido; Diplos; Draconia; Eden; Exxilon; The Eye of Orion; Foamasi homeworld; Frontios; Hakol; Jagaroth homeworld; Jenggel; Kastopheria; Kastria; Kembel; Krynoid homeworld; Macra homeworld; Mandragora Helix; Manussa; Mechanus; Mimosa II; Mongo; Ogros; Oseidon; Peladon; Pesca; Phaester Osiris; Raaga; Refusis II; Rhuta III; Rigel; Sarn; Schirr homeworld; Sirius IV; Solos; Spiridon; Tara; Tarron; Telos; Terileptil homeworld; Tigella; Trion; Uxarieus; Vedela; Vega Nexos; Vorella; Xeraphas; Xoanon's world; Yemaya; Zanak; Zolfa-Thura; Zygon homeworld
Some early BBC publicity placed Skaro within Earth's galaxy, but most fans and authors agree that the Daleks' homeworld is located in another galaxy altogether. Dialogue in "Terror of the Autons" indicates that Gallifrey may lie within this galaxy, but the designation of Mutter's Spiral first given in "The Dealy Assassin," and a location of "250 million light-years away" given in the 1996 television movie both indicate that Gallifrey is also located elsewhere in the Universe.