کهکشان راه شیری HD

Text at http://howfarawayisit.com/documents/ In this segment of our "How far away is it" video book, we cover the structure of the Milky Way galaxy. After a brief history of what we thought going into the 20th century and how that changed, we give a high-level description of the three main components: the galactic center with its black hole, the galactic disk with its spiral arms, and the galactic halo stretching far out in all directions.

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