MILKY WAY

The Milky Way is a barred spiral galaxy with a diameter between 150,000 and 200,000 light-years .It is estimated to contain 100–400 billion stars and more than 100 billion planets. The Solar System is located at a radius of about 27,000 light-years from the Galactic Center , on the inner edge of the Orion Arm, one of the spiral-shaped concentrations of gas and dust. The galactic center is an intense radio source known as Sagittarius A*, assumed to be a supermassive black hole of 4.100 (± 0.034) million solar masses

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The Milky Way is visible from Earth as a hazy band of white light, some 30° wide, arching across the night sky. In night sky observing, although all the individual naked-eye stars in the entire sky are part of the Milky Way, the term "Milky Way" is limited to this band of light.The light originates from the accumulation of unresolved stars and other material located in the direction of the galactic plane. Dark regions within the band, such as the Great Rift and the Coalsack, are areas where interstellar dust blocks light from distant stars. The area of sky that the Milky Way obscures is called the Zone of Avoidance.