Early voyagers to the polar regions often saw the northern lights, a remarkable luminous display that some considered to be mists emanating from the earth. Capron was one of the first scientists to discuss the chemical and physical nature of the phenomenon. By the 1950s, it was accepted that the northern lights are caused by the interaction of high-energy electrons from the Sun with atoms in the Earth’s upper atmosphere.

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Systema cosmicum is the Latin translation of Galileo’s great 1632 treatise, Dialogo sopra i due massimi sistemi del mondo . . . (Dialogue concerning the two chief world systems). Galileo set the Dialogo as a conversation among three people about the problems and merits of the classical Earth-centered model of the solar system versus the newer Sun-centered one. Galileo’s endorsement of the latter arrangement so infuriated papal authorities that he was kept under house arrest for the remainder of his life. He first published his treatise in Italian as an appeal to the larger public, and then again in 1641, in Latin, the language of the intellectual world. This copy was previously owned by the Dutch Protestant theologian Alhart de Raedt (born 1645), who annotated the book extensively.

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Shortly after the invention of the telescope, Galileo in 1609 constructed one for himself and turned it to the heavens. He quickly published this brief account of his amazing discoveries, the first work of modern observational astronomy. In it, Galileo describes his revolutionary sightings of craters on the Moon, individual stars in the Milky Way, and the four largest moons of Jupiter. Publication of Sidereus nuncius triggered a chain of events that shook the foundation of European thought and launched an intellectual voyage that would take us deeper into the universe. This copy is from the collection of Herbert McLean Evans (1882-1971), a pioneer in collecting books about the history of science.

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A founder of the Aeronautical Society of Great Britain, James Glaisher described the first recorded balloon ascensions undertaken specifically for scientific research. Glaisher and his colleagues studied atmospherics and meteorology, and they nearly died from asphyxiation and hypothermia when their balloon rose too high.

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This volume is a republication of Robert Goddard's pioneering research in liquid-fuel rocket development. Goddard, considered the founding father of modern rocketry, laid the groundwork for America’s space program. The Smithsonian supported his research beginning in 1916 and published his first publication on rocketry in 1919. The Institution, despite mockery from skeptics, published further research in 1936.

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A great pioneer in the study of the stars, William Herschel was appointed private astronomer to the king of England in recognition of his 1781 discovery of the planet Uranus. In this paper, he made his first, not entirely successful attempt at a scientific explanation of the structure of the Milky Way galaxy, opening a debate that continues to this day. The folding plate illustrates his concept of how the galaxy would appear to an outside observer. Herschel also claimed that dim nebulous patches in the sky were galaxies just like our own.

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Hevelius’s personal observatory in Danzig was the best-equipped facility of its kind in the world. A champion of the "long-focus" telescope, sometimes more than 100 feet in length, Hevelius was an expert builder who constructed many of his own instruments. The first volume of this work describes his "celestial machines" in great detail, and its engravings often depict Hevelius using the devices, frequently in concert with his wife and collaborator, Elisabetha. This book was in the collection of Herbert McLean Evans (1882-1971), a pioneer in collecting books about the history of science.

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Imposing mathematical harmony on the skies, Kepler proposed that the planetary orbits nested one inside the other, with each planet (at the time, thought to be six) alternating with one of the five Platonic "solids" (geometric figures such as the cube). This elegant model addressed both the number of planets and the spacing of their orbits. Kepler’s idea, while not fully worked out, attempted to clarify the spatial organization of the solar system while arguing that geometry was an innate part of the divine plan of creation.

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Ley, a paleontologist, engineer, and theorist on conditions on other planets and space, edited this book of essays written by famous rocket scientists, including Hermann Oberth, Walter Hohmann, and Guido von Pirquet.

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When Newton presented his concepts about the behavior and characteristics of light, particularly his assertion that white light is composed of a spectrum of colors, he posed a number of questions intended to stimulate further research. In the 1718 revision of his 1704 work, Newton extended his original 16 queries to 31; these discourses were considered the most provocative parts of the book. Through the queries, Newton speculated that a fluid, or "aether," pervaded all of space and provided the medium through which light could travel. Robert Smith (1689-1768), Plumian Professor of Astronomy at Cambridge University and author of the most influential textbook on optics in the 1700s, owned this copy and annotated it heavily.

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Regiomontanus, one of the first publishers of astronomical material, developed an almanac series that was popular enough to continue after his death. The almanacs contained planetary positions for a particular year as calculated from astronomical tables, freeing astronomers from performing the laborious task themselves. This 1499 copy contains numerous annotations to the almanac and its eclipse predictions.

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Austrian astronomer Georg Peurbach began a new Latin translation in 1460 of Ptolemy’s compendium of Greek astronomical knowledge, and Regiomontanus, a German astronomer and mathematician, completed it before 1463. The authors clarified obscure passages and offered a concise and comprehensible summary of the Almagest. The work, the first appearance in print of Ptolemy’s treatise, had an unprecedented impact on Renaissance astronomers and played a key role in the development of modern astronomy. The Smithsonian copy is heavily annotated and contains numerous mathematical drawings.

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In 1762, a large fireball entered the Earth’s atmosphere and exploded over Germany. Silberschlag provided a good description of the event along with engravings of meteors, the fireball’s path, and its ultimate fiery explosion. Not until the 1800s did scientists begin to concede that fireballs and meteorites might have extraterrestrial origins. Prior to that, it was difficult to conceive how boulders could fall from the sky, and many believed that meteorites were simply rocks struck by lightning.

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Piazzi Smyth was the first astronomer to seriously advocate that astronomical observations would be greatly improved if done at high altitudes. His report to the British Admiralty on his expedition to the Canary Islands greatly influenced the next generation of astronomers, including Samuel P. Langley (1834-1906), third Secretary of the Smithsonian, to whom he sent this copy. It includes annotations by the two men as well as a pasted-in spectrum by Piazzi Smyth and a letter from him to Langley.

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