Littleness Of our Planet (Earth).

Knowledge of Earth's location in the universe has been shaped by 400 years of telescopic

observations, and has expanded radically in the last century. Initially, Earth was believed to be the center of the universe, which consisted only of those planets visible with the naked eye and an outlying sphere of fixed stars. After the acceptance of theheliocentric model in the 17th century, observations by William Herschel and others showed that the Sun lay within a vast, disc-shaped galaxy of stars. By the 20th century, observations of spiral nebulae revealed that our galaxy was one of billions in an expanding universe, grouped into clusters and superclusters. By the 21st century, the overall structure of the visible universe was becoming clearer, with superclusters forming into a vast web of filaments and voids. Superclusters, filaments and voids are likely the largest coherent structures that exist in the Universe. At still larger scales (over 1000 megaparsecs) the Universe becomes homogeneous meaning that all its parts have on average the same density, composition and structure.

Since there is believed to be no "center" or "edge" of the universe, there is no particular reference point with which to plot the overall location of the Earth in the universe. The Earth is at the center of the observable universe because its observability is determined by its distance from Earth. Reference can be made to the Earth's position with respect to specific structures, which exist at various scales. It is still undetermined whether the universe is infinite.
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