The "Gaia Sausage" is so-called because of the characteristic sausage shape of the population in a chart of velocity space, in particular a plot of radial ( v r {\displaystyle {\boldsymbol {v}}_{r}} ) versus azimuthal velocity ( v θ {\displaystyle {\boldsymbol {v}}_{\theta }} ) of stars (See spherical coordinate system), using data from the Gaia Mission.[1] The stars that have merged with the Milky Way have orbits that are highly elongated.