Is there anything interesting about the Sun's location in the Milky Way?

Well, we are located inside what appears to be a roughly spherical zone about 600 light years across, where most of the interstellar medium has been swept out. This 'Local Bubble' may have been created 100,000 years ago when a supernova went off.

The Sun and the Local Bubble are located on the inner edge of what is called the 'Orion Arm' or 'Orion Spur' in the great spiral pattern of the Milky Way. As we look in the direction of Cygnus, we are looking down this Arm and see all of the star clusters and interstellar dust clouds that are part of the arm which extends from Cygnus, across Perseus, and off towards Carina. If we look off towards Perseus, careful studies of the reddening of starlight show that we encounter this arm about 300 - 400 parsecs from the sun. If we look towards Sagittarius, we do not encounter the spiral arm interior to the Sun's location for about 1500 parsecs or so. Towards Cygnus, a sharp increase in obscuration occurs at a distance of 700 parsecs causing the 'Great Rift' in Cygnus.

Galactic cartography is a challenging subject which is still being fine tuned to help us better understand where the Sun is located in the Milky Way, and just what the Milky Way would look like from the outside.


Copyright 1997 Dr. Sten Odenwald
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