~ Rittenhouse Medal Award ~

Picture Gallery

The Rttenhouse Medal is awarded for outstanding achievement in the science of Astronomy.

Dr. Frank Schlessinger, then Director of the Yale Observatory, was the first person to be awarded a Certificate Medal.  The medal was one of those originally minted to commemorate the Bi-Centenary of the birth of David Rittenhouse on April 8, 1932.  It was thought fitting by the members to include one of the medals as a souvenir along with the Certificate of Honorary Membership.

Ten men  received an Honorary Membership and the Souvenir Medal.





Dr. Frank Schlessinger Oct. 17, 1933

Director Yale Observatory
Originally from Yerkes Observatory, he was also president of the American Astronomical society.  His main research interest was the improvement of parallax measurements.  Results of his investigations are world-renowned and he is considered the leading authority in that area of research.

Dr. Robert G. Aitken Oct. 16, 1934

Director Lick Observatory
He made systematic surveys of binary stars, discovering thousands, measuring their positions visually and calculating orbits for many.  His works allowed orbit determinations which increased astronomer's knowledge of stellar masses.

Dr. Harlow Shapley Oct. 19, 1935

Mount Wilson Observatory
Calibrated Henrietta S. Leavitts's period-luminosity relation for Cepheid variable stars and used it to determine distances to globular clusters.  He boldly and correctly proclaimed that globulars outline the Milky Way and the galaxy's center was thousands of light years away in the direction of Sagittarius.  

Dr. Robert McMath Dec. 11, 1936

Director McMath-Hulbert Observatory
Served as chairman of the association of Universities for Research in Astronomy.  The National Solar Observatory is the crowning achievement of Dr. McMath who was known for his expertise in solar physics and building solar telescopes. The observatory  is co-named along with Dr. Pierce.

Dr. Armin O. Leuschner Apr. 22, 1937

Berkley Astronomical Department
Director University of California
His research was in orbit theory, and he determined or refined the orbits of numerous asteroids and comets, but his most important contribution to astronomy was as an educator.

Dr. Knut Lundmark Mar. 24, 1938

Professor of Astronomy, University of Lund, Sweden
Plotted the radial velocity galaxies against their estimated distances.  He made rough determinations of the distances to other galaxies by comparing their sizes and brightness to that of M31.  Lundmark concluded that there may be a relationship between galactic red-shift and distance, but "not a very definite one." 1924

Dr.  Gustavus Wynne Cook Mar. 6, 1940

Director Cook Observatory
Investigator in Astronomical Science, The observatory named for Dr. Cook; now named the Flower and Cook Observatory, is one of the oldest astronomical research institutions in America: Founded in 1895.  Originally in Malverne PA, and now relocated on the University of Pennsylvania Campus atop the David Rittenhouse Laboratory.

Dr. John A. Miller May 10, 1940

Director Emeritus, Sproul Observatory

Dr. Forest Ray Moulton Mar. 3, 1943 Secretary, American Association for the Advancement of Science
Mr. Samuel Fels Nov. 9, 1943

Philanthropist and Donor of Fels Planetarium
One of Philadelphia's most prominent philanthropists.  He took an active interest in, and gave generous support to, civic, scientific, cultural, and educational causes. 




~ Silver Medal Award ~

There is no record in the Rittenhouse minutes of further awards of honorary Memberships and/or souvenir Rittenhouse Medals. 

In 1952 the Society decided to establish a silver medal to be awarded to astronomers for noteworthy achievement in astronomical science.  The silver medal is cast from the die (obverse) used for the Bi-Centennial Rittenhouse Medal.





Dr. Gerard P. Kuiper

April 16,1952 Director Yerkes Observatory
April 16, 1952 Kuiper discovered two moons of planets: Uranusís moon Miranda in 1948 and Neptuneís moon Nereid in 1949. In 1944 he discovered that Saturnís moon Titan had an atmosphere of methane. He is considered the father of modern planetary science. He was chief scientist for the Ranger lunar-probe program and identified landing sites for the Apollo moon missions. His greatest contribution was the prediction in 1951 that a belt of minor planets existed outside Neptuneís orbit that was the source of short-period comets. This belt, now called the Kuiper Belt is also the location of possible other planets.
Dr. Harlow Shapley March 18,1953

Director Harvard Observatory
There he studied the Magellanic clouds and made catalogs of galaxies. He wrote many books and was an important popularizer of science. He founded and developed an outstanding graduate school.  Cofounder of UNESCO, he played a major role in national and international affairs.

Dr. Otto Struve April 23, 1954

President International Astronomical Union:
He made detailed spectroscopic investigations of stars.  He directed four observatories including McDonald which he founded and where a telescope is named for him.

Sir Harold Spencer Jones April 22, 1955 Astronomer Royal of England
Apr. 22, 1955 From 1933 to 1955 Spencer Jones was the tenth Astronomer Royal. He determined the distance from Earth to the sun by triangulating the distance to the asteroid Eros, refining the near accurate measurement made by David Rittenhouse in 1769. He published a paper in 1939 showing that the Earthís rotation was not uniform and could no longer be used as an accurate clock. He worked at the Royal Observatory in Greenwich and supervised its move to Herstmonceux Castle in Sussex.
Dr. Lyman Spitzer, Jr. May 19, 1958 Director Princeton University Observatory
He was the first to propose putting a large telescope in space.  The Hubble Space Telescope was based on his concepts.  The Infrared Spitzer Space Telescope was named for him.
Dr. Bengt Stromgren April 1, 1959

Professor; Institute for Advanced Study, Princeton:
Known for his theory of the ionized gas clouds around hot stars.  He calculated the relative abundances of the elements in the sun and other stars.

Dr. Fred Hoyle  January 6, 1960

Plumian Professor of Astronomy, Cambridge University
He coined the term Big Bang but never accepted that theory for the origin of the universe.  Hoyle believed in the steady-state theory.  He advanced a theory that infections on Earth resulted from microorganisms arriving from distant places in the universe.

Cecelia Payne Gaposchkin 1961

Professor Harvard University:
The first woman to become a full  professor at Harvard University.  Her dissertation was said to be the best one in 20th century astronomy.  She was ahead of her time showing that hydrogen and helium were a major constituent of stars.

Peter Van De Kamp 1965

Director Sproul Observatory, Swarthmore College
He studied nearby stars measuring their movements.  He started a search for planets orbiting other stars.  He was the president of the Rittenhouse Astronomical Society in 1944.

Martin Schwarzschild



Professor; Princeton University
His book, "Structure and Evolution of the Stars," was used by astrophysicists to apply computers to the computation of stellar models.  His Stratosphere project sent balloons with instruments to obtain data of the sun, other stars and planets of our solar system in the 1950s and 1960s.

Helen Sawyer Hogg 1967 Harvard Observatory
Encouraged women to study and enter the science profession.  She developed techniques for measuring the distance to galaxies beyond the Milky Way.  Her research was on variable stars in globular clusters.  She was program director for the National Science Foundation, first female president of the Royal Canadian Institute and founded the Canadian Astronomical Society.  In 1976 she became a Companion of the Order of Canada-one of the highest honors in the nation.
Allan Sandage 1968 He found the first optical counterpart to a radio source that would be identified as a quasar.  His research has been in stellar astronomy and observational cosmology.  He was involved in determining the ages of the oldest objects known.
Carl Sagan 1980  
Carolyn and Eugene Shoemaker 1988  
Clyde Tombaugh 1990  




~ Gallery of Past Events ~    

The undertaking was near maddening! During his 14-year search for planets beyond Neptune, Clyde Tombaugh photographed 70 percent of the night sky and blinked 90,000 square degrees of star fields.  Some plates had more than a million star images each.  The search areas are plotted on his copy of Norton's Star Atlas. Courtesy Clyde Tombaugh Astronomy Magazine  April 1991


Dr. Howard McClenahan, Secretary of The Franklin Institute and Director of the Museum; Samuel Fels; and Dr. James Stokley, the Institute's Associate Director for Astronomy, admire the Mark Zeiss II planetarium instrument in the Fels Planetarium, circa 1933

Clyde Tombaugh receives the Rittenhouse Medal from Milton Friedman, president of the Rittenhouse Astronomical Society, in Philadelphia, Pennsylvania.  Photograph by Robert Summerfield, Sky and Telescope Magazine April 1991


Carolyn and
Eugene Shoemaker

Shoemakers in the Bloom Observatory with RAS members

Venus Transit on the Rooftop with Derrick Pitts

President Milton Friedman takes a closer look 

Milt Rosenthal and the continual upgrade of his telescope

Milt Rosenthal (past officers and telescope builders of RAS)


Alan Daroff solar observing with his self designed gear

Milt Freidman, Joy Crist, Val Gonzales

Mr. and Ms. Barringer and Dr. Friedman


Derrick Pitts, Chief Astronomer, Franklin Institute


Sally Ride - First American female astronaut in space  1985 

Alexander Wolszczan - First to discover extrasolar planet (currently PSU professor)

Dr. Milt Friedman, Harrison Schmitt (Apollo 17, One of the last Astronauts to step foot on the Moon)


Dr. Milt Friedman
Astronomy Fair, Franklin Hall 1981


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