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Sagittarius

Sagittarius is a constellation in the southern sky that lies in the direction of the center of the Milky Way galaxy. It is rich in deep-sky objects and is home to Sagittarius A*, the supermassive black hole at the Milky Way’s core.

Source: nasa.gov

APODs including "Sagittarius"

Sagittarius Dwarf to Collide with Milky Way

16/02/1998

Sagittarius Dwarf to Collide with Milky Way
Image Credit: NASA Astronomy Picture of the Day

Our Galaxy is being invaded. Recent observations indicate that in the next 100 million years, the Sagittarius Dwarf galaxy will move though the disk of our own Milky Way Galaxy yet again . The Sagittarius Dwarf (Sgr), shown as the extended irregular shape below the Galactic Center, is the closest of 9 known small dwarf spheroidal galaxies that orbit our Galaxy. Don't worry, our Galaxy is not in danger, but no such assurances are issued for the Sagittarius Dwarf: the intense gravitational tidal forces might pull it apart. Oddly, however, Sgr's orbit indicates that is has been through our Galaxy several times before, and survived! One possibility is that Sgr contains a great deal of low-density dark matter that hold it together gravitationally during these collisions.