Pure Science



Harvard Spectral Classification Scheme

"The modern stellar spectral classification scheme (also known as the Harvard Spectral Classification Scheme) was created by Annie Jump Cannon through her examination of spectra from 1918 to 1924. Originally, the scheme used capital letters running alphabetically, but was later reordered to reflect the surface temperatures of stars. In order of decreasing temperature, these types were O, B, A, F, G, K and M. Three additional categories also in the scheme: R, N, and S types, were later realized to represent stars with peculiar heavy-metal abundances.

Coastal and Marine Ecological Classification Standard

"The Coastal and Marine Ecological Classification Standard (CMECS) provides a national framework for organizing information about coasts and oceans and their living systems. It provides a structure for developing and synthesizing data so that ecosystems can be identified, characterized, and mapped in a standard way across regional and national boundaries. CMECS also supports status and trend monitoring activities, policy development, restoration planning, and fisheries management. The standard complements existing wetland and upland classification systems.