Harlow Shapley - The Astronomer By Chance

In our life, some of the best decisions are taken only by chance. We plan to do something else, but end up with something completely unexpected. The same thing happened with Harlow Shapley, who took up the most important decision of his career, by a mere chance. Today, On his 134th birth Anniversary, let's take a dig into the life of this "Astronomer by Chance".

Harlow Shapley
Image Courtesy : tonyortega.org

Early life

The son of a farmer and schoolteacher, Harlow Shapley was born on November 2, 1985 in a farmhouse near Carthage, Missouri. He received the equivalent of a fifth-grade education in a nearby rural school. Later, he took a short business course in Pittsburg. A year later, he worked briefly as a police reporter. Determined to qualify for college, he and his younger brother John applied to the high school in Carthage. Sadly, they were turned down. So, they attended the Presbyterian Carthage Collegiate Institute, from where Harlow graduated after two semesters.

Taking up Astronomy by Chance

In 1907, Shapley enrolled at the University of Missouri, intending to enter the projected School of Journalism. But, destiny had some others plans for him. He learned that the opening of the School of Journalism has been postponed for a year. So, he decided to study the first subject he came across in the course directory. Doing so, he came across Archaeology. But, he rejected it, as he claimed that he could not even pronounce it. So, moving on with the list, he chose the next subject, Astronomy. Thus, he took up astronomy almost by accident, a beautiful accident indeed !

Remarkable discoveries

In 1911, Shapley started working with results given by Henry Norris Russell. He began finding the dimensions of stars in a number of binary systems from measurements of their light variation when they eclipse one another. Moreover, Shapley showed that Cepheid variables cannot be star pairs that eclipse each other. He was the first to propose that they are pulsating stars.

In 1914, Shapley joined the staff of the Mount Wilson Observatory, Pasadena, California. Using the 1.5-metre reflecting telescope there, he made a study of the distribution of the globular clusters in the Milky Way Galaxy. Shapley used the Cepheid luminosity-period relationship to measure the distances to nearby globular clusters.  He used other methods to measure more distant clusters that had no visible Cepheids. His final estimates were not far from the modern values.

Harlow Shapley plotted the location of these clusters. As a result, an overall picture of the Milky Way galaxy emerged. Contrary to the expectations, The Sun turned out to be located in the galactic disk, about two–thirds of the way out from the galactic center. Thus, he deduced that the Sun lies near the central plane of the Milky Way Galaxy and was not at the centre but some 30,000 light-years away. His work led to the first realistic estimate for the actual size of the Galaxy and thus was a milestone in galactic astronomy.

Location of Sun in Milky Way
Image Courtesy: sciencevibe.com

The Great debate of 1920

In 1920 , a great debate took place which paved way for the Extragalactic astronomy. Harlow Shapley along with Heber D. Curtis, participated in this "Great Debate" on the nature of nebulae and galaxies and the size of the Universe. This debate took place on April 26, 1920, in the hall of the United States National Academy of Sciences in Washington DC. Shapley took the side that spiral nebulae (which we now call galaxies) are inside our Milky Way. Whereas, Curtis took the side that the spiral nebulae are 'island universes' far outside our own Milky Way and comparable in size and nature to our own Milky Way. Curtis won the debate. But, after the debate, Harlow was hired as director of the Harvard College Observatory, which was believed to be Shapley's primary goal for participating in the debate.

Miscellaneous Contributions :

In addition to his studies of the Galaxy, Shapley studied the neighbouring galaxies, especially the Magellanic Clouds. He found that galaxies tend to occur in clusters, and he termed them as metagalaxies. In 1953 he proposed the “liquid water belt” theory. This theory stated that a planet has to be at a certain distance from its star to develop an atmosphere and have liquid water, and therefore life. This concept is what we now call the habitable zone. Shapley was also one of the most important contributors in solving the puzzle of the odd cloud-like objects collectively referred to as nebulae. Shapley has published several notable books during his lifetime. In 1940s, Shapley helped the government to establish funded scientific associations, including the National Science Foundation. He is also responsible for the addition of the "S" in UNESCO (United Nations Educational, Scientific and Cultural Organization).

Awards and honours:

For his contribution to science and remarkable discoveries, Harlow Shapley has received several awards and honours. These include the Henry Draper Medal of the National Academy of Sciences in 1926, the Rumford Prize of the American Academy of Arts and Sciences in 1933, the Gold Medal of the Royal Astronomical Society in 1934, the Bruce Medal of the Astronomical Society of the Pacific in 1939, the Franklin Medal in 1945, the Henry Norris Russell Lectureship of the American Astronomical Society in 1950 and many more. Apart from this, even a crater on moon, an asteroid and a supercluster have also been named after him.

Who knew that the man who is taking up Astronomy just because he is not having any other option will one day, make amazing some amazing revelations in this field. He is truly one of the most significant astronomers this world has ever witnessed. Happy birthday Genius!

Also Read : Astronomy Events in November 2019

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