Today is the birthday of American Astronomer Harlow Shapley (born 1885, died 1972), who made the first accurate estimate of the size of the Milky Way galaxy. He came to astronomy by an interesting route-after dropping out of school with a fifth grade education, he returned years later and finished a six year high school program in two years as class valedictorian. He applied to the University of Missouri to study but the School of Journalism opening was postponed for a year so he decided to study the very first thing in the course directory. He couldn’t pronounce archeology and astronomy was next. Although he is best known for his role in calculating the size of the Milky Way, he stood in opposition to many key astonomers of the day, and was often wrong in his assessment of contemporary theory. He was also the author of many books on astronomy and had an active role in the formation of the National Academy of Science. To his credit, he was just as often right-his stature and importance as an astronomer cannot be understated.
The first attempt to describe the shape of the Milky Way and the position of the Sun within it was carried out by William Herschel in 1785. Herschel counted the number of stars in different regions of the visible sky and produced a diagram of the shape of the galaxy with the Solar System close to the center, adhering to the Copernican theory of the universe.
In European culture the name Milky Way is comes from its resemblance to a dim ”milky” glowing band arching across the night sky. The term is a translation of the Latin phrase via lactea meaning Milky Way or road, which came from the Ancient Greek γαλαξίας κύκλος (galaktikos kyklos). γαλαξίας (galaxias) which came from the root γαλακτ-, γάλα (milk) became by association the word for all collections of stars we now know as galaxies.
Photos of the Milky Way over Europe courtesy Herb Raab.