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
Hottentot (racial term) "hodmandod" in the years around 1700. The reduced Afrikaans/Dutch form "hotnot" has also been borrowed into South African English as an offensive term for black people. In seventeenth-century Dutch, "Hottentot" was at times used to denote all black people (synonymously with "Kaffir"), but at least some speakers were careful to use the term "Hottentot" to denote what they thought of as a race distinct from the supposedly darker-skinned "Kaffirs". This distinction between the non-Bantu "Cape Blacks" and the Bantu was noted as early as 1684 by French anthropologist François Bernier. The idea that "Hottentot" referred strictly to the non-Bantu peoples