[10] Officially discovered in 1994, by Rodrigo Ibata, Mike Irwin, and Gerry Gilmore,[11] Sgr dSph was immediately recognized as being the nearest known neighbor to the Milky Way at the time.

Although it is one of the closest companion galaxies to the Milky Way, the main parent cluster is on the opposite side of the Galactic Center from Earth, and consequently is very faint, although covering a large area of the sky.

[18][20] Based on its current trajectory, the Sgr dSph main cluster is about to pass through the galactic disc of the Milky Way within the next hundred million years, while the extended loop-shaped ellipse is already extended around and through our local space and on through the Milky Way galactic disc, and in the process of slowly being absorbed into the larger galaxy, calculated at 10,000 times the mass of Sgr dSph.

[5] At first, many astronomers thought that Sgr dSph had already reached an advanced state of destruction, so that a large part of its original matter was already mixed with that of the Milky Way.

However, Sgr dSph still has coherence as a dispersed elongated ellipse, and appears to move in a roughly polar orbit around the Milky Way as close as 50,000 light-years from the galactic core.

Although it may have begun as a spherical object before falling towards the Milky Way, Sgr dSph is now being torn apart by immense tidal forces over hundreds of millions of years.

[21][22] A 2020 study concluded that collisions between the Sagittarius Dwarf Spheroidal Galaxy and the Milky Way triggered major episodes of star formation in the latter, based on data taken from the Gaia project.