While similar to dwarf elliptical galaxies in appearance and properties such as little to no gas or dust or recent star formation, they are approximately spheroidal in shape and generally have lower luminosity.
Despite the radii of dSphs being much larger than those of globular clusters, they are much more difficult to find due to their low luminosities and surface brightnesses.
[2] The Sloan Digital Sky Survey has resulted in the discovery of 11 more dSph galaxies as of 2007[7] By 2015, many more ultra-faint dSphs were discovered, all satellites of the Milky Way.
[9] Each dSph is named after constellations they are discovered in, such as the Sagittarius dwarf spheroidal galaxy, all of which consist of stars generally much older than 1–2 Gyr that formed over the span of many gigayears.
[14] Furthermore, there is evidence that the UMa2, a dwarf spheroidal galaxy in the Ursa Major constellation, experiences strong tidal disturbances from the Milky Way.