The Milky Way |
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The Milky Way  |
The Galaxy We Live In The Milky Way is a spiral galaxy which is the home of our Solar System together with at least 200 billion other stars, their planets, thousands of clusters and nebulae. A spiral galaxy can be described as having a bulge in the center, surrounded by a disk (flat, moving) and spherical halo. Compared with other galaxies, the Milky Way is very large - its mass is probably between 750 billion and one trillion solar masses, its diameter about 100,000 light years. Galaxies, which are made up of stars, gas and dust, rotate very slowly. Our Sun, one of many stars in our Milky Way Galaxy, completes a circuit around the Milky Way every 250 million years. The term "milky" originates from the hazy band of white light appearing across the celestial sphere visible from Earth, which comprises stars and other material lying within the galactic plane. The Greek philosopher, Democritus (450 BC – 370 BC) was the first known person to claim that the Milky Way consists of distant stars. |
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