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Spectroheliograph
The spectroheliograph is an instrument used in astronomy which captures a photography, photographic image of the Sun at a single wavelength of light, a monochromatic image. The wavelength is usually chosen to coincide with a optical spectrum, spectral wavelength of one of the chemical elements present in the Sun. It was developed independently by George Ellery Hale and Henri-Alexandre Deslandres in the 1890s and further refined in 1932 by Robert Raynolds McMath, Robert R. McMath to take motion pictures. The instrument comprises a prism (optics), prism or diffraction, diffraction grating and a narrow slit that passes a single wavelength (a monochromator). The light is Focus (optics), focused onto a photographic medium and the slit is moved across the disk of the Sun to form a complete image. It is now possible to make a H-alpha, filter that transmits a narrow band of wavelengths which produces a similar image, but spectroheliographs remain in use. See also * Spectrohelioscope * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
George Ellery Hale
George Ellery Hale (June 29, 1868 – February 21, 1938) was an American astrophysicist, best known for his discovery of magnetic fields in sunspots, and as the leader or key figure in the planning or construction of several world-leading telescopes; namely, the 40-inch refracting telescope at Yerkes Observatory, 60-inch Hale telescope, 60-inch Hale reflecting telescope at Mount Wilson Observatory, 100-inch Hooker telescope, 100-inch Hooker reflecting telescope at Mount Wilson, and the 200-inch Hale Telescope, 200-inch Hale reflecting telescope at Palomar Observatory. He played a key role in the foundation of the International Union for Cooperation in Solar Research and the National Research Council (United States), National Research Council, and in developing the California Institute of Technology into a leading research university. Early life and education George Ellery Hale was born on June 29, 1868, in Chicago, Illinois, to William Ellery Hale and Mary Browne.Adams 19 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Henri-Alexandre Deslandres
Henri Alexandre Deslandres (; 24 July 1853 – 15 January 1948) was a French astronomer, director of the Meudon and Paris Observatories, who carried out intensive studies on the behaviour of the atmosphere of the Sun. Biography Deslandres' undergraduate years at the École Polytechnique were played out against the aftermath of the Franco-Prussian War and the chaos of the Paris Commune so, on graduation in 1874, he responded to the continuing military tension with the emerging Germany by embarking on a military career. Rising to the rank of captain in the engineers, he became increasingly interested in physics and, in 1881, resigned his commission to join Alfred Cornu's laboratory at the École Polytechnique, working on spectroscopy. He continued his spectroscopic work at the Sorbonne, earning his doctorate in 1888 and created the deslandres table, which finds numerical patterns in spectral lines that paralleled the work of Johann Balmer and were to catalyse the development ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Robert Raynolds McMath
Robert Raynolds McMath (May 11, 1891 – January 2, 1962) was an American solar astronomer. McMath was a bridge engineer, businessman, and astronomer. His father, Francis C. McMath, had made a fortune as a bridge builder. They both had a keen interest in amateur astronomy. So in 1922, the McMaths, along with Judge Henry S. Hulbert founded the McMath–Hulbert Observatory in Lake Angelus, Michigan. It was deeded to the University of Michigan in 1931, McMath served as the director of the McMath–Hulbert Observatory until 1961. In 1932, McMath extended the functionality of the spectroheliograph so that it could record motion pictures of the Sun. This machine is known as a ''spectroheliokinematograph''; with it, he took astonishing moving pictures of solar storms, showing features on the Sun's surface that lasted from seconds to days. In 1933, he and his father received the Franklin Institute's John Price Wetherill Medal. He was elected to the American Philosophical Societ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectrohelioscope
A spectrohelioscope is a type of solar telescope designed by George Ellery Hale in 1924 to allow the Sun to be viewed in a selected wavelength of light. The name comes from Latin- and Greek-based words: "Spectro," referring to the optical spectrum, "helio," referring to the Sun, and "scope," as in telescope. The basic spectrohelioscope is a complex machine that uses a spectroscope to scan the surface of the Sun. The image from the objective lens is focused on a narrow slit revealing only a thin portion of the Sun's surface. The light is then passed through a prism or diffraction grating to spread the light into a spectrum. The spectrum is then focused on another slit that allows only a narrow part of the spectrum (the desired wavelength of light for viewing) to pass. The light is finally focused on an eyepiece so the surface of the Sun can be seen. The view, however, would be only a narrow strip of the Sun's surface. The slits are moved in unison to scan across the whole surface ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helioscope
A helioscope is an instrument used in observing the Sun and sunspots. The helioscope was first used by Benedetto Castelli (1578–1643) and refined by Galileo Galilei (1564–1642). The method involves projecting an image of the sun onto a white sheet of paper suspended in a darkened room with the use of a telescope. The first ''machina helioscopica'' or helioscope was designed by Christoph Scheiner (1575 –1650) to assist his sunspot observations. (Latin) In the context of modern astroparticle physics, the term ''helioscope'' can also refer to an experiment that seeks to observe hypothetical particles (such as the axion) produced inside the sun. Examples of such helioscope experiments searching for axions include the CERN Axion Solar Telescope and International Axion Observatory. See also *Solar telescope * Heliometer *Spectroheliograph The spectroheliograph is an instrument used in astronomy which captures a photography, photographic image of the Sun at a single waveleng ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
H-alpha
Hydrogen-alpha, typically shortened to H-alpha or Hα, is a deep-red visible spectral line of the hydrogen atom with a wavelength of 656.28 nm in air and 656.46 nm in vacuum. It is the first spectral line in the Balmer series and is emitted when an electron falls from a hydrogen atom's third- to second-lowest energy level. H-alpha has applications in astronomy where its emission can be observed from emission nebulae and from features in the Sun's atmosphere, including solar prominences and the chromosphere. Balmer series According to the Bohr model of the atom, electrons exist in quantized energy levels surrounding the atom's nucleus. These energy levels are described by the principal quantum number ''n'' = 1, 2, 3, ... . Electrons may only exist in these states, and may only transit between these states. The set of transitions from ''n'' ≥ 3 to ''n'' = 2 is called the Balmer series and its members are named sequentially by Greek letters: *''n'' = 3 to ''n'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Focus (optics)
In geometrical optics, a focus, also called an image point, is a point where ray (optics), light rays originating from a point on the object vergence (optics), converge. Although the focus is conceptually a point, physically the focus has a spatial extent, called the circle of confusion, blur circle. This non-ideal focusing may be caused by optical aberration, aberrations of the imaging optics. Even in the absence of aberrations, the smallest possible blur circle is the Airy disc caused by diffraction from the optical system's aperture; diffraction is the ultimate limit to the light focusing ability of any optical system. Aberrations tend to worsen as the aperture diameter increases, while the Airy circle is smallest for large apertures. An image, or image point or region, is in focus if light from object points is converged almost as much as possible in the image, and defocus aberration, out of focus if light is not well converged. The border between these is sometimes define ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monochromator
A monochromator is an optics, optical device that transmits a mechanically selectable narrow band of wavelengths of light or other radiation chosen from a wider range of wavelengths available at the input. The name is . Uses A device that can produce monochromatic light has many uses in science and in optics because many optical characteristics of a material are dependent on wavelength. Although there are a number of useful ways to select a narrow band of wavelengths (which, in the visible range, is perceived as a pure color), there are not as many other ways to easily select any wavelength band from a wide range. See #Applications, below for a discussion of some of the uses of monochromators. In hard X-ray and neutron radiation, neutron optics, crystal monochromators are used to define wave conditions on the instruments. Techniques A monochromator can use either the phenomenon of optical dispersion in a Prism (optics), prism, or that of diffraction using a diffraction gratin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diffraction
Diffraction is the deviation of waves from straight-line propagation without any change in their energy due to an obstacle or through an aperture. The diffracting object or aperture effectively becomes a secondary source of the Wave propagation, propagating wave. Diffraction is the same physical effect as Wave interference, interference, but interference is typically applied to superposition of a few waves and the term diffraction is used when many waves are superposed. Italian scientist Francesco Maria Grimaldi coined the word ''diffraction'' and was the first to record accurate observations of the phenomenon in 1660 in science, 1660. In classical physics, the diffraction phenomenon is described by the Huygens–Fresnel principle that treats each point in a propagating wavefront as a collection of individual spherical wavelets. The characteristic pattern is most pronounced when a wave from a Coherence (physics), coherent source (such as a laser) encounters a slit/aperture tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prism (optics)
An optical prism is a transparent optical element with flat, polished surfaces that are designed to refract light. At least one surface must be angled—elements with two parallel surfaces are ''not'' prisms. The most familiar type of optical prism is the triangular prism, which has a triangular base and rectangular sides. Not all optical prisms are geometric prisms, and not all geometric prisms would count as an optical prism. Prisms can be made from any material that is transparent to the wavelengths for which they are designed. Typical materials include glass, acrylic and fluorite. A dispersive prism can be used to break white light up into its constituent spectral colors (the colors of the rainbow) to form a spectrum as described in the following section. Other types of prisms noted below can be used to reflect light, or to split light into components with different polarizations. Types Dispersive ''Dispersive prisms'' are used to break up light into its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Scribner's Sons
Charles Scribner's Sons, or simply Scribner's or Scribner, is an American publisher based in New York City that has published several notable American authors, including Henry James, Ernest Hemingway, F. Scott Fitzgerald, Kurt Vonnegut, Marjorie Kinnan Rawlings, Stephen King, Robert A. Heinlein, Thomas Wolfe, George Santayana, John Clellon Holmes, Don DeLillo, and Edith Wharton. The firm published ''Scribner's Magazine'' for many years. More recently, several Scribner titles and authors have garnered Pulitzer Prize, Pulitzer Prizes, National Book Award, National Book Awards and other merits. In 1978, the company merged with Atheneum Books, Atheneum and became The Scribner Book Companies. It merged into Macmillan Inc., Macmillan in 1984. Simon & Schuster bought Macmillan in 1994. By this point, only the trade book and reference book operations still bore the original family name. After the merger, the Macmillan and Atheneum adult lists were merged into Scribner's, and the Scribn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
