Geocentric model explanation in terms of the Earth's revolution about the sun. In 1838, astronomer Friedrich Wilhelm Bessel measured the parallax of the star 61 Cygni successfully, and disproved Ptolemy's claim that parallax motion did not exist. This finally confirmed the assumptions made by Copernicus, providing accurate, dependable scientific observations, and conclusively displaying how distant stars are from Earth. A geocentric frame is useful for many everyday activities and most laboratory experiments, but is a less appropriate choice for solar system mechanics and space travel. While a heliocentric frame is most useful in those cases, galactic and extragalactic astronomy is easier if
National Register of Historic Places listings in Central Chicago National Register of Historic Places listings in Central Chicago Currently there are 124 National Register of Historic Places listings in Central Chicago, out of 354 listings in the City of Chicago. Central Chicago includes 3 of the 77 well-defined community areas of Chicago: the historic business and cultural center of Chicago known as the Loop, as well as the Near North Side and the Near South Side. The combined area is bounded by Lake Michigan on the east, the Chicago River on the west, North Avenue (1600 N.) on the north, and 26th Street (2600 S.) on the south. This