Celsius Celsius scale are defined by absolute zero and the triple point of Vienna Standard Mean Ocean Water (VSMOW), a specially purified water. This definition also precisely relates the Celsius scale to the Kelvin scale, which defines the SI base unit of thermodynamic temperature with symbol K. Absolute zero, the lowest temperature possible, is defined as being exactly 0 K and −273.15 °C. The temperature of the triple point of water is defined as exactly . This means that a temperature difference of one degree Celsius and that of one kelvin are exactly the same. In 1742, Swedish astronomer Anders Celsius
Christian Mayer (astronomer) able to continue his astronomical observations and studies. He applied for and was granted in December 1765 a Fellowship of the Royal Society. He is most noted for pioneering the study of binary stars, although his equipment was ill-suitable for distinguishing between true binaries and coincident star alignments. In 1777-78 he compiled a catalog of 80 double stars, which he published in 1781. During his lifetime he became a member of numerous learned societies. He died in Heidelberg. Christian Mayer (astronomer) Christian Mayer (August 20, 1719 – April 16, 1783) was a Czech-German Catholic priest, astronomer and teacher. He was