HALE SOLAR LABORATORY
The Hale Solar Laboratory is important because of its association with its owner-builder, George Ellery Hale. Hale was an internationally famous scientist, a trustee behind the endowment of the Huntington Library and Art Gallery in San Marino, California, and a trustee and organizer of the California Institute of Technology.
The Hale Solar Laboratory was Hale's office and workshop for the later years of his life. Hale's scientific contributions were many, especially in the area of astronomy. Hale was one of the first scientists to compare observations in physics laboratories here on earth to what is seen in the heavens. He, more than anyone else, was the person most responsible for the rise of the science of modern astrophysics in the United States.
The Hale Solar Laboratory was also the site of many scientific discoveries, the most famous being Hale's refinement of the spectrohelioscope, a device that made it possible to observe the hydrogen-rich prominences of the sun.
LICK OBSERVATORY BUILDING
The 36-inch Clark refractor housed in the Lick Observatory building was the first large telescope erected on a site chosen for its astronomical advantages, rather than for convenience in the builder's backyard, or on a university campus. The location of the telescope on Mount Hamilton proved to be an excellent choice and provided an example that has been followed from 1888 until the present day. The discoveries of early Lick astronomers began a tradition of excellence at Lick that has had a profound impact in shaping the history of American astronomy in the twentieth century. By combining excellent equipment, a favorable location, and the proximity to the resources of the University of California, Lick established the pattern for large modern observatories that has continued to this day and has left a major imprint on modern astronomy.
LICK CROSSLEY 36-INCH REFLECTOR
The Crossley 36-inch reflector at the Lick Observatory was the first of a long line of metal-film-on-glass modern reflecting telescopes that have dominated major astronomical advances for the past century. In addition, the Crossley has produced more scientific results than any other telescope of its size including several historically important studies in stellar evolution, the structure and spectra of planetary nebulae, and the discovery and spectral analysis of faint variable stars in young clusters. The Crossley also contributed to studies that confirmed the expansion of the universe.
MOUNT WILSON OBSERVATORY
The establishment of Mount Wilson Observatory in 1904, by American astronomer George Ellery Hale, brought a new era to the science of astronomy. The Snow horizontal telescope and the two solar tower telescopes were the first major instruments placed on Mount Wilson. Completion of the 60-inch reflector in 1908 and the 100-inch Hooker reflector in 1917 made Mount Wilson the home of the two largest telescopes in existence and the center of the astronomical world. These telescopes represented a quantum leap in mechanical and optical engineering capability. They laid the technological foundation for all large modern telescopes. Many of the major advances and greatest names in 20th-century astronomy are associated with the Mount Wilson Observatory, including Edwin P. Hubble, who in 1929 used the 100-inch Hooker reflector to gather data that showed the universe to be in a regular state of expansion, thereby providing the first clues to the origin of the universe.
PALOMAR OBSERVATORY 200-INCH REFLECTOR
The construction and delivery of the Pyrex glass disk for the Palomar 200-inch reflector in 1936 marked a watershed in the history of astronomy. With the successful casting of this large mirror, the Palomar project, conceived by George Ellery Hale (1868-1938), and funded with a grant of $6 million by the Rockefeller Foundation, moved toward the completion of the largest reflecting telescope in the world by 1948. In the 40 years since the completion of the Palomar project, the 200-inch reflector remains at the leading edge of research in the sciences of astronomy and astrophysics and stands today as a monument to George Ellery Hale and his efforts to produce the finest instruments in the world to answer the fundamental questions concerning the origin and nature of the universe.
PALOMAR 48-INCH OSCHIN (SCHMIDT) TELESCOPE
Although not as well known as the 200-inch Hale reflector, the 48-inch Oschin (Schmidt) telescope at the Palomar Observatory has performed invaluable scientific research and has prepared the way for many of the important discoveries made by the 200-inch. This instrument was first used in 1950 to carry out two surveys of the Northern Hemisphere, one through a red filter and one through a blue, so that a comparison of the two black and white prints would reveal how cool (red) or how hot (blue) a star was. The surveys involved taking 1758 plates of the northern sky and recorded stars never seen before. The Palomar sky survey is the standard reference atlas for deep sky observation and provides a base line with which to measure changes in deep sky observation targets in future surveys. It is used as a standard reference tool for all modern observatories doing deep sky observation.
UNITED STATES NAVAL OBSERVATORY
The United States Naval Observatory is the oldest scientific institution in the Navy, being first established in 1830 as the Depot of Charts and Instruments. The observatory is most noted for its work in study of positional astronomy and timekeeping. The Naval Observatory, along with the Royal Observatory in Greenwich, England, and the Pulkovo Observatory in the Soviet Union, is one of the few places in the world that continually observes and redefines the positions of the sun, moon, planets, and stars. The United States Naval Observatory is the only place in the United States where precise instruments measure celestial motions to provide accurate time and other astronomical data which are essential for safe navigation at sea, in the air, and in space.
UNIVERSITY OF ILLINOIS OBSERVATORY
The University of Illinois Observatory is significant because of its association with the development of the selenium photoelectric cell which revolutionized the science of astronomical photoelectric photometry--the measurement of celestial magnitudes. The research was conducted on the 12-inch Warner and Swasey refractor telescope located in the second-story equatorial room of the 1896 brick observatory. The development of the selenium cell was done by Joel Stebbins (1878-1966), in the years from 1907 to 1922, while he was the director of the University of Illinois Observatory. As a result of Stebbins work at Illinois with the photoelectric cell, photoelectric photometry became the standard technique in determining stellar magnitudes. The determination of stellar magnitudes is one of the most fundamental measurements in the field of astronomy.
BLUE HILL METEOROLOGICAL OBSERVATORY
The Blue Hill Meteorological Observatory is the foremost structure associated with the history of weather observations in the United States. Founded by Abbott Lawrence Rotch on February 1, 1885, the observatory took a leading role in the newly emerging science of meteorology and was the scene of many of the first scientific measurements of upper atmosphere weather conditions using kites to carry weather instruments aloft. Knowledge of wind velocities, air temperature and relative humidity at various levels came into use as vital elements in weather prediction due to techniques developed at this site. By 1895 the observatory was the source of weather forecasts of remarkable accuracy. The observatory remains active to this day, continuing to add to the data base of weather observations now over 100 years old, and stands as a monument to the science of meteorology in the United States.
GAITHERSBURG LATITUDE OBSERVATORY
The Gaithersburg Latitude Observatory is significant for its association with the study of polar motion, and for its symbolic value in representing an important and long-lived program of international scientific cooperation. Established in 1899 by the International Geodetic Association, the International Polar Motion Service was a cooperative effort among scientists worldwide to study the Earth's wobble on its rotational axis. The Gaithersburg Latitude Observatory was one of six observatories around the world (in the United States, Russia, Japan, and Italy) commissioned under this program.
Between 1900 and 1960 these observatories were the best source of information on polar motion available to scientists. Data supplied by the six latitude observatories have been used in hundreds of scientific papers and studies investigating the geophysics of the earth. The observatories have enabled geodesists to better understand the size and shape of the earth and astronomers to adjust their observations for the effects of polar motion. In more practical terms, the work done by the observatories contributed to studies attempting to determine earthquake mechanisms and the elasticity of the earth, and to predict climate variations. The space program has also benefited from this work; polar motion study is necessary to determine orbit patterns of spacecraft and satellites, and aids tracking techniques used in deep space navigation.
The latitude observatories made a major contribution to science on an international scale. The research undertaken in these small, simple structures fueled work done in earth motion studies for decades. From its construction in 1899 until the obsolescence of man-operated telescopic observation forced its closing in 1982, the Gaithersburg Latitude Observatory played an integral role in this important scientific endeavor.
The Horn Antenna, at the Bell Telephone Laboratories in Holmdel, New Jersey, is significant because of its association with the research work of two radio astronomers, Dr. Arno A. Penzias and Dr. Robert A. Wilson. In 1965 while using the Horn Antenna, Penzias and Wilson stumbled on the microwave background radiation that permeates the universe. Cosmologists quickly realized that Penzias and Wilson had made the most important discovery in modern astronomy since Edwin Hubble demonstrated in the 1920s that the universe was expanding. This discovery provided the evidence that confirmed George Gamow's and Abbe Georges Lemaitre's "Big Bang" theory of the creation of the universe and forever changed the science of cosmology--the study of the history of the universe--from a field for unlimited theoretical speculation into a subject disciplined by direct observation. In 1978 Penzias and Wilson received the Nobel Prize for Physics for their momentous discovery.
The Cincinnati Observatory is one of the oldest functioning observatories in the United States. Founded in 1843, it was located on Mount Adams until 1873, when it was moved to its present site on Mount Lookout, just off Observatory Avenue, in Cincinnati. The present observatory building dates from 1873.
The Cincinnati Observatory was the first fully equipped observatory in the midwest and is associated with the productive careers of such famous American astronomers as Ormsby MacKnight Mitchel (1809-1862), who published the Sidereal Messenger, the first attempt to bring astronomy to the masses in the United States, and Paul Herget (1908-1981), who was the world's foremost authority on the computation of planetary orbits. In addition, the Cincinnati Observatory is associated with Cleveland Abbe (1838-1916), a meteorologist who began to issue daily weather bulletins in 1869. Abbe's work proved so popular with the American public that steps were taken to establish a permanent government institution to continue this service--the United States Weather Bureau.
The Allegheny Observatory at the University of Pittsburgh is significant because of its association with the careers of astronomers Samuel Pierpont Langley (1834-1906), James Edward Keeler (1857-1900), and telescope maker John Alfred Brashear (1840-1920).
Langley was professor of astronomy and physics at the University from 1867 to 1887 and director of the Allegheny Observatory. During that time he invented the bolometer and used it in 1878 to make spectral observations of solar and lunar radiation. His paper on The Bolometer and Radiant Energy (1881) became a scientific classic. While Langley was the director, the Allegheny Observatory was the leading American observatory on matters relating to the study of solar physics.
James Edward Keeler succeeded Langley as director of the Allegheny Observatory and used the 13-inch Fitz-Clark refractor with a spectroscope to show, in 1895, that the rings of Saturn were rotating as a unit but that the inner boundary had a considerably shorter period than the outer. This was the first observational evidence that the rings were not solid but consisted of discrete particles circling the planet at different speeds.
John Alfred Brashear was named acting director of the Allegheny Observatory after Keeler's departure for the Lick Observatory in 1898. Brashear was a self-taught optician whose service to astronomy began in 1876 when he began to make astronomical telescopes. Over the years of his active career Brashear not only made both of the larger telescopes used at the Allegheny Observatory, but came to be recognized as one of the best telescope makers of his day. In the years since Brashear's death in 1920, the Allegheny Observatory has used his telescope (the Thaw refractor) to do fundamental work in the field of astrometry, including the search for stars whose oscillations betray the presence of invisible companions.
The Stellafane Observatory in Springfield, Vermont, possesses national significance for its pioneering role in the development of amateur telescope making and popular astronomy in the United States. The Stellafane complex contains both the original clubhouse of the first organized group of amateur telescope makers in the country, the Springfield Telescope Makers, Inc., and the first large optical telescope built and owned by that kind of amateur society. Since their construction in 1924 and 1930, respectively, the clubhouse and observatory have remained in continuous use by the Springfield Telescope Makers, and have been preserved essentially in original condition. Stellafane now holds an international reputation which attracts thousands of amateur telescope makers and astronomers to annual conventions held on the site.
REBER RADIO TELESCOPE
The Reber Radio Telescope was the first parabolic antenna specifically designed and built to do research in the newly emerging field of radio astronomy. The telescope was designed and built by Grote Reber, an amateur astronomer and electronics expert from Wheaton, Illinois, who from 1937 until after World War II, was the world's only active radio astronomer. The telescope design is the forerunner of the majority of present day radio telescopes.
Yerkes Observatory was founded by American astronomer George Ellery Hale in 1897 and represents his revolutionary concept for an observatory that would also be a physical laboratory. To the majority of astronomers at the time an observatory was simply a place for a telescope and observer. For example, when the new United States Naval Observatory in Washington, DC, was completed in 1893, there was no provision for a darkroom or for a spectroscopic laboratory. In contrast, Yerkes Observatory was provided with laboratories and a variety of mechanical and electronical workshops. Yerkes represented the wave of the future and established the modern observatory as a research institution where the astronomer, using the disciplines of chemistry and physics, supported by engineering and optics workshops, could apply his talents to the understanding of the wonders of the universe. In the years since its founding by George Ellery Hale, Yerkes has attracted the most famous astronomers in the world, and contributed significantly to the sciences of astronomy and astrophysics.