Recent Posts

Archive

Tags

No tags yet.

Two Missouri Astronomers Helped Find Our Place in the Heavens


Astronomer Copernicus, or Conversations with God 1873 By Majeko

It was one of astronomy's harshest lessons when 16th century astronomer Nicolaus Copernicus revealed that Earth and human kind do not enjoy a privileged place in the cosmos. Ever since the original Copernican Revolution that put the Sun at the center of our solar system not Earth, our planet has continued to be shone in an increasingly diminutive light when it comes to its station in the cosmos. As Missourians though, we may find consolation that using a biographical measure we are still special astronomically speaking. Missouri was the birthplace of two famous astronomers, and since Copernicus none have done more to help humankind find our place among the stars.

Astronomers Harlow Shapley and Edwin Hubble were both born in Missouri. Shapley discovered the center and dimension of our galaxy. Hubble discovered that our Milky Way Galaxy is but one of billions of galaxies racing away from each other in an expanding universe.

SHAPELY MEASURED OUR GALAXY

Shapley was born November 2, 1885 on a farm just outside of Nashville Missouri. Originally, Shapley made it only through to the 6th grade due to the families lack of finances. In 1907, after completing his belated high school education in a span of a year and a half, Shapley would attend Missouri University in the hope of studying journalism. But the opening of the journalism school had been delayed and he claims to have picked astronomy as his major since it was close to the top of the

catalogue. After graduation, Shapley did his graduate work at Princeton. He worked at the famous Mount Wilson Observatory and eventually became the director of the Harvard Observatory.

Shapley studied RR Lyrae variables in globular clusters, which are ancient groups of stars that circle what he determined to be the center of the Milky Way Galaxy. Using the known luminosity of the variables Shapley was able to calculate not only the direction of, but the distance to the center of our galaxy. For the record it is about 25,000 light years away in the general direction of Sagittarius.

He gave an idea to its shape and dimension of our galaxy where before there had only been amorphous fields of stars and nebula.

HUBBLE PROVED THAT THERE ARE OTHER GALAXIES BEYOND OUR OWN MILKY WAY

Although most everyone has heard of Edwin Hubble's namesake telescope many don't know that he was born in Marshfield Missouri in 1889.

Hubble earned his bachelor of science degree at the University of Chicago and then went on to earn a Master's degree from The Queens College, Oxford where he specialized in jurisprudence. He had promised his dying father he would study law, but never practiced as an attorney. In 1917, after a short stint as a high school teacher, Hubble went on to earn his PhD in astronomy from the University of Chicago. He then enlisted in the army and rose to the rank of Major during the first world war. Upon returning from overseas, Hubble joined the staff of Palomar Observatory where his work dramatically changed the scope of the known universe.

Using Cepheid Variables, a type of star that changes brightness at a rate linked to its absolute magnitude (how bright it is compared to other stars), Hubble proved definitively that the Andromeda Nebula was itself a galaxy. The dimension of the spiral nebula and whether or not it transcended the bounds of the Milky Way had been long debated. It was Hubble's work that convinced Harlow Shapely, who had held that the great nebula was part of our own Milky Way Galaxy, that it was indeed its own island universe.

Hubbles work established that the universe was made up of galaxies beyond our own Milky Way and that the scale of the universe is tremendous even in astronomical terms.

Hubble also discovered that the recessional velocity of galaxies increases with their distance from the earth. This relationship is one of the most central and profound cosmological facts ever discovered. It has led to a model of an expanding universe. The realization that our universe is not static but dynamic and expanding was a surprising paradigm shift. Even Albert Einstein attempted to introduce a "gravitational constant" into his field equations in order to accommodate a static universe. A move he later rued as his "biggest blunder." Subsequently, Hubble's discovery became central to all work in cosmology, including Einstein's.

SMALL BUT PROUD

One of astronomy's harshest lessons is that Earth is not the center of the universe about which the heavens revolve. But at least as Missourian's we can take some pride in the fact that through the work of Shapley and Hubble, our state has done more than any other in finding our place among the stars.

Nasa image of M 101