Question: The Sagittarius Dwarf Spheroidal Galaxy, a loop-shaped galaxy of the Milky Way, is which type of the three main classes of galaxy originally described by Edwin Hubble in "The Realm of the Nebulae?"

The Carina Dwarf Spheroidal Galaxy is a dwarf galaxy in the Carina constellation.  It was discovered in 1977 with the UK Schmidt Telescope by Cannon et al.  The Carina Dwarf Spheroidal galaxy is a satellite galaxy of the Milky Way and is receding from it at 230 km/s.  The diameter of the galaxy is about 1600 light-years, which is 75 times smaller than the Milky Way.  Most of the stars in the galaxy formed 7 billion years ago, although it also experienced bursts of star formation about 13 and 3 billion years ago.  It is also being tidally disrupted by the Milky Way galaxy. <SEP>  Unlike flat spiral galaxies with organization and structure, they are more three-dimensional, without much structure, and their stars are in somewhat random orbits around the center. An elliptical galaxy is a type of galaxy having an approximately ellipsoidal shape and a smooth, nearly featureless brightness profile.  They are one of the three main classes of galaxy originally described by Edwin Hubble in his 1936 work "The Realm of the Nebulae", along with spiral and lenticular galaxies.  Elliptical galaxies range in shape from nearly spherical to highly flat and in size from tens of millions to over one hundred trillion stars. Originally Edwin Hubble hypothesized that elliptical galaxies evolved into spiral galaxies, which was later discovered to be false.  Stars found inside of elliptical galaxies are on average much older than stars found in spiral galaxies. <SEP> 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 consists of four globular clusters, the main cluster having been discovered in 1994.  Sgr dSph is roughly 10,000 light-years in diameter, and is currently about 70,000 light-years from Earth, travelling in a polar orbit (i.e. an orbit passing over the Milky Way’s galactic poles) at a distance of about 50,000 light-years from the core of the Milky Way (about 1/3 the distance of the Large Magellanic Cloud).  In its looping, spiraling path, it has passed through the plane of the Milky Way several times in the past. <SEP> An intermediate spiral galaxy is a galaxy that is in between the classifications of a barred spiral galaxy and an unbarred spiral galaxy.  It is designated as SAB in the galaxy morphological classification scheme.  By definition, a galaxy is a congregation of stars held together by gravity.  The first intermediate spiral galaxy discovered is the Milky Way, by Galileo, in 1610.  He was the first person with a telescope powerful enough to make such a discovery.  Before Galileo, it was thought that all bright objects in the sky were either the planets in the Solar System, moons, comets, or stars.  Until the beginning on the twentieth century, astronomers did not know the size of the Universe, but speculated it to be about as big as the Milky Way.  In 1920, at the National Academy of Science, there was a big debate between Harlow Shapley and Heber D. Curtis on whether nebulae are small globular clusters surrounding the Milky Way, or separate galaxies located farther away.  Nothing was resolved at the debate; neither side was able to provide conclusive evidence to prove their side correct over their opponent.  In 1923, Edwin Hubble resolved the matter with a photograph that he took of the Andromeda Galaxy.  What he found in his photograph was a very bright light source pulsing at a certain rate, a Cepheid variable, located outside the Milky Way.  This can be used to determine the distance to it.  Hubble proved that the Universe was full of galaxies, and disproved that the Milky Way was the extent of the Universe.  There are many types of galaxies in the Universe, elliptical, barred spiral galaxies; they vary in shape and size, but on average spiral galaxies are the most abundant.