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| | Milky Way Spiral Structure |
 | | The arms of the Milky Way, at least near the solar neighborhood in our Galaxy, are typically named for the constellations where (in the direction of which) more substantial parts of them are situated. |
 | | The next inner arm, sometimes labelled "-I", is called the Sagittarius or Sagittarius-Carina Arm, the next outer arm, labelled "+I", is the Perseus Arm. |
 | | These arms can be traced by deepsky objects, namely diffuse nebulae, open star clusters and associatons, (type II and Ib/Ic) supernova remnants, and main sequence stars of so-called "early" (hot) spectral types. |
| www.seds.org /messier/more/mw_arms.html (438 words) |
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