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
Truce term of Schoolchildren". They found truce terms varied according to geographical location, with the exception of "pax". In some places, more than one term was current and often four or five were known, although usually only one term predominated. Schools bordering two linguistic regions honoured both. The words used in urban areas were often at odds with words used in the surrounding countryside. The Opies recorded around 45 truce terms plus variations. The most widely used were "barley", "fainites", "kings", "crosses", "keys", "skinch", "cree" and "scribs". "Barley" was recorded by the Opies as the prevailing term in east Scotland and the