- In astronomy, the main sequence is a classification of stars which appear on plots of stellar color versus brightness as a continuous and distinctive band. Stars on this band are known as main-sequence stars or dwarf stars, and positions of stars on and off the band are believed to indicate their physical properties, as well as their progress through several types of star life-cycles. These are the most numerous true stars in the universe and include the Sun. Color-magnitude plots are known as Hertzsprung–Russell diagrams after Ejnar Hertzsprung and Henry Norris Russell.
- John C. Calhoun (Wikipedia)
John Caldwell Calhoun (/kælˈhuːn/; March 18, 1782 – March 31, 1850) was an American statesman and political theorist who served as the seventh vice president of the United States from 1825 to 1832. Born in South Carolina, he adamantly defended American slavery and sought to protect the interests of white Southerners. Calhoun began his political career as a nationalist, modernizer and proponent of a strong federal government and protective tariffs. In the late 1820s, his views changed radically, and he became a leading proponent of states’ rights, limited government, nullification, and opposition to high tariffs. Calhoun saw Northern acceptance of those policies as a condition of the South’s remaining in the Union. His beliefs heavily influenced the South’s secession from the Union in 1860 and 1861. He was the first of two vice presidents to resign from the position, the second being Spiro Agnew, who resigned in 1973.