Now Playing: It has a hugh black hole in the center (brightest area)
Size and Shape of the Milky Way
The Milky Way is a large galaxy comprising an estimated 200 billion stars (some estimates range as high as 400 billion) arrayed in the form of a disk, with a central elliptical bulge (some 12,000 light-years in diameter) of closely packed stars lying in the direction of Sagittarius.
http://en.wikipedia.org/wiki/Milky_way_galaxy
It is surrounded by a flat disk marked by six spiral arms—four major and two minor—which wind out from the nucleus like a giant pinwheel. Because of these arms, the Milky Way was classified as a spiral galaxy. However, increasing evidence indicates that the Milky Way probably has a bar or barlike structure of new, bright stars in its central region.
This would modify its classification to a barred spiral or an intermediate type between barred and “normal” spiral. Our sun is situated in one of the smaller arms, called the Local or Orion Arm, that connect the more substantial next inner arm and the next outer arm. The sun lies roughly two thirds of the way from the center of the disk, which is some 28,000 light-years distant, and in the galactic plane.
When we look in the plane of the disk we see the combined light of its stars as the Milky Way. The diameter of the disk is c.100,000 light-years; its average thickness is 10,000 light-years, increasing to 30,000 light-years at the nucleus.
Large pic of Milky Way: http://pictures.aol.com/galleries/philcutrara1/20c0nl-wKQUpbzF4PUDR471tOEMVxafzJ-Jb/large/
Course on Astro Physics: http://homepages.wmich.edu/~korista/phys325.html
Black Holes: http://journals.aol.com/philcutrara1/Our-Milky-Way/
A black hole "shines" with Hawking radiation. The escaping member of a virtual particle pair carried away energy from the black hole, and the black hole loses mass as a result. Eventually the black hole loses all its energy, or equivalently mass, and evaporates.
Math of the above: http://library.thinkquest.org/C007571/english/advance/english.htm Many Parallel Universes:
http://www.bbc.co.uk/science/horizon/2001/paralleluni.shtml
Branes Crashed Into One Another: http://www.sciencenews.org/articles/20010922/bob9.asp
