The Astronomy Book

119 See also: The Tychonic model 44–47 ■ Mapping southern stars 79 ■ Messier objects 87 ■ Space telescopes 188–95 ■ A digital vi ...

120 A PRECISE MEASUREMENT OF THE STARS THE STAR CATALOG IN CONTEXT KEY ASTRONOMER Edward C. Pickering (1846–1919) BEFORE 1863 An ...

121 See also: The sun’s spectrum 112 ■ The characteristics of stars 122–27 ■ Classifying star spectra 128 ■ Measuring the univer ...

CLASSIFYING THE STARS ACCORDING TO THEIR SPECTRA REVEALS THEIR AGE AND SIZE THE CHARACTERISTICS OF STARS ...

...

124 A merican astronomer Annie Jump Cannon was the early 20th-century’s leading authority on the spectra of stars. When she died ...

125 around the the world, noticed more variety in the detail. She devised a more complex system of 22 groups designated by Roman ...

126 additional dimension, creating the Yerkes classification system, otherwise called the MKK system after William Morgan, Phili ...

127 they make up 3 percent of the main sequence and are a little larger than the sun. The spectra of these stars contain medium- ...

128 See also: The sun’s spectrum 112 ■ Analyzing starlight 113 ■ The star catalog 120–21 ■ The characteristics of stars 122–27 ■ ...

129 See also: Galileo’s telescope 56–63 ■ The surface of the sun 103 ■ The sun’s vibrations 213 ■ Maunder (Directory) 337 A meri ...

THE KEY TO A DISTANCE SCALE OF THE UNIVERSE MEASURING THE UNIVERSE ...

THE KEY TO A DISTANCE SCALE OF THE UNIVERSE MEASURING THE UNIVERSE ...

132 S ome of the most important, but often most challenging, measurements for astronomers to make have been the distances to ext ...

133 Milky Way institutions. Under the supervision of its director, Edward C. Pickering, the Observatory employed many men to bui ...

134 later. These are stars that regularly vary in brightness with a period (cycle length) that could be anything from one to mor ...

135 Astronomical Observatory of Harvard College in 1908. Then, in 1912, after further study, which included plotting graphs of t ...

136 Following these calibrations, Hertzsprung was able to establish a system for determining the distance to any Cepheid variabl ...

137 was also employed by Hubble in his discovery of the relationship between the distance and recessional velocity of galaxies, ...

138 STARS ARE GIANTS OR DWARFS REFINING STAR CLASSIFICATION IN CONTEXT KEY ASTRONOMER Henry Norris Russell (1877–1957) BEFORE 19 ...