CLYDE WILLIAM TOMBAUGH - FIRST DAY COVER SIGNED CO-SIGNED BY: JAMES A. VAN ALLEN - HFSID 13004
Sale Price $252.00
ASTRONOMERS: CLYDE TOMBAUGH and JAMES VAN ALLEN
Both astronomers sign a First Day Cover honoring Copernicus.
First Day Cover signed: "J.A. Van Allen" and "Clyde W. Tombaugh", 6½x3½. FDC honoring astronomer Nicolaus Copernicus, 8-cent stamp affixed, postmarked Washington, D.C., April 23, 1973. Clyde W. TOMBAUGH (1906-1997) was hired in 1929 as an assistant by the Lowell Observatory in New Mexico to continue the search for a planet beyond Neptune, which had been initiated by Percival Lowell. Tombaugh used a blink microscope to compare photographs of a small part of the night sky and detect the planet. After ten months of painstaking comparisons, on February 18, 1930 he found Pluto in the constellation Gemini. James VAN ALLEN is best known for his work in magnetospheric physics. He developed proposals for the launch of a scientific satellite as part of the research program conducted during the International Geophysical Year of 1957-1958. His Explorer spacecraft, launched in 1958, returned important scientific data about the radiation belts circling the Earth, named the Van Allen Belts in his honor. Fine condition.
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