A galaxy is a great cloud of stars gas and dust bound

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Unformatted text preview: . How big is the Milky Way Galaxy? 100,000 light years Sun NASA Our galaxy is a disk-shaped collection of over one hundred billion stars, 100,000 light years across 16 Our solar system is just one system in our galaxy. A galaxy is a great cloud of stars, gas, and dust bound together by the combined gravity of all the matter. Our galaxy, the Milky Way, is a disk-shaped collection of over one hundred billion stars, 100,000 light years across. Like many others, it has graceful spiral arms winding outward through the disk. Our Sun is within the one of the arms about 26,000 light years from the center. Even on our one- to- ten billion scale, the galaxy is astronomical in size! Sun Earth NASA Our scale model would still be ~100 million km across! 17 Scaling our 100,000 light year diameter galaxy by a factor of 10 billion creates a model of our galaxy 100 million km across! If Earth marks the location of the Sun in the model, then our model of the galaxy stretches well within the orbit of Venus. Clearly, we need to scale the galaxy further to create a practical model. Scale by another factor of 1 billion: Our galaxy on a football field ‣ ‣ ‣ ‣ ‣ Scaled by a factor of 10 billion billion! 1 meter = 1,000 light years! Galactic center: midfield Sun: 25 yard line Alpha Centauri: 4mm away from the Sun!!! Sun NASA Google Maps 18 We increase the scale by another factor of 1 billion, to 1 to 10-billion-billion (a 1 followed by 19 zeros). At this scale, 1 meter equals 1,000 light years, our model is 100 meters across and the galaxy fits on a football field. At this scale, the Sun is the size of a hydrogen atom (100 picometers across), and Alpha Centauri is just 4 mm away from the Sun! If the galactic center is at midfield, the our solar system would be located on about the 25 yard line. Thought QuesNon Suppose you tried to count the more than 100 billion stars in...
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