Mass of milky galaxy

Name
(in distance) Diameter (ly) orbital
radius
(ly) Type Discovered
I Canis Major Dwarf - 25,000 Irr 2003
II Sagittarius Dwarf - 81,000 Irr 1994
III LMC - 160,000 Irr 1519
IV SMC - 190,000 Irr 1519
V Ursa Minor Dwarf - 205,500 dE4 1954
VI Draco Dwarf - 248,000 dE0 1954
VII Sculptor Dwarf Galaxy - 254,000 dE3 1937
VIII Sextans Dwarf - 257,500 dE3 1990
IX Carina Dwarf - 283,500 dE3 1977
X Ursa Major Dwarf - 330,000 - 2005
XI Fornax Dwarf - 427,000 dE2 1938
XII Leo II - 701,000 dE0 1950
XIII Leo I - 890,000 dE3 1950
The Milky Way is a barred spiral[1] galaxy of the Local Group. Although the Milky Way is but one of billions of galaxies in the universe, the Galaxy has special significance to humanity as it is the home of the Solar System. The Greek philosopher Democritus (450 BC–370 BC) was the first known person to claim that the Milky Way consists of distant stars.

The term "milky" originates from the hazy band of white light appearing across the celestial sphere visible from Earth, which comprises stars and other material lying within the galactic plane. The galaxy appears brightest in the direction of Sagittarius, towards the galactic center. Relative to the celestial equator, the Milky Way passes as far north as the constellation of Cassiopeia and as far south as the constellation of Crux, indicating the high inclination of Earth's equatorial plane and the plane of the ecliptic relative to the galactic plane.The fact that the Milky Way divides the night sky into two roughly equal hemispheres indicates that the solar system lies close to the galactic plane.

The main disk of the Milky Way Galaxy is about 80,000 to 100,000 light-years in diameter, about 250,000 to 300,000 light-years in circumference, and outside the Galactic core, about 1,000 light-years in thickness. It is estimated to contain 200[2] billion stars but this number might reach 400 billion [1] if small-mass stars predominate. As a guide to the relative physical scale of the Milky Way, if the galaxy were reduced to 130 km (80 mi) in diameter, the solar system would be a mere 2 mm (0.08 inches) in width. The Galactic Halo extends outward, but is limited in size by the orbits of the two Milky Way satellites, the Large and the Small Magellanic Clouds, whose perigalacticon is at ~180,000 light-years.[3] As detailed in the Structure section below, new discoveries indicate that the disk extends much farther than previously thought.

The Milky Way's visual absolute magnitude is −20.9[4]

As of 2006, the Milky Way's mass is thought to be about 5.8×1011 M☉[10][11][12] comprising 200 to 400 billion stars. Its integrated absolute visual magnitude has been estimated to be -20.9.