Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. As the millennium progressed, humans mapped the continents , circumnavigated the globe , and determined the composition of the Earth . The Earth started as the center of everything , but became a planet placed in the Solar System , which became placed in a Galaxy , which became placed in the Local Group of Galaxies , which became placed in an expanse so vast we call it just the Universe . As millennium two ends people generally know what Earth looks like from afar , and how it is that all of humanity is confined to the surface of this fragile and watery globe .
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