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Spectroheliograph
The spectroheliograph is an instrument used in astronomy which captures a photographic image of the Sun at a single wavelength of light, a monochromatic image. The wavelength is usually chosen to coincide with a 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 R. McMath to take motion pictures. The instrument comprises a prism or diffraction grating and a narrow slit that passes a single wavelength (a monochromator). The light is 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 filter that transmits a narrow band of wavelengths which produces a similar image, but spectroheliographs remain in use. See also * Spectrohelioscope * Helioscope * Heliometer A heliometer (from Greek ἥλιος ''hḗlios'' "sun" and ''measure'') is a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
George Ellery Hale
George Ellery Hale (June 29, 1868 – February 21, 1938) was an American solar astronomer, 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 reflecting telescope at Mount Wilson Observatory, 100-inch Hooker reflecting telescope at Mount Wilson, and the 200-inch Hale reflecting telescope at Palomar Observatory. He also played a key role in the foundation of the International Union for Cooperation in Solar Research and the 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 1939, p. 181. He is descended from Thomas Hale of Watton-on-Stone, Hertfordshire, England, whose son emi ... [...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 o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Robert Raynolds McMath
Robert Raynolds McMath (May 11, 1891 – January 2, 1962) was a U.S. solar astronomer. Robert R. McMath (1891-1962) was a bridge engineer, businessman, and astronomer. Robert's 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, Robert served as the director of the McMath–Hulbert Observatory until 1961. In 1932, Robert 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. Robert McMath was an advise ... [...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 In optics, a diffraction grating is an optical component with a periodic structure that diffracts light into several beams travelling in different directions (i.e., different diffraction angles). The emerging coloration is a form of structur ... 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 wav ... [...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 (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 A solar telescope is a special purpose telescope used to observe the Sun. Solar telescopes usually detect light with wavelengths in, or not far outside, the visible spectrum. Obsole ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
H-alpha
H-alpha (Hα) is a specific deep-red visible spectral line A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to ident ... in the Balmer series with a wavelength of 656.28 nm in air and 656.46 nm in vacuum; it occurs when a hydrogen electron falls from its third to second lowest energy level. H-alpha light is the brightest hydrogen line in the visible spectral range. It is important to astronomers as it is emitted by many emission nebulae and can be used to observe features in the Sun's Sun#Atmosphere, atmosphere, including solar prominences and the chromosphere. Balmer series According to the Bohr model of the atom, electrons exist in Quantum, quantized energy levels surrounding the atom's atomic nucleus, nucleus. These energy levels are described by the principal quantum number ''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 light rays originating from a point on the object converge. Although the focus is conceptually a point, physically the focus has a spatial extent, called the blur circle. This non-ideal focusing may be caused by aberrations of the imaging optics. In the absence of significant aberrations, the smallest possible blur circle is the Airy disc, which is caused by diffraction from the optical system's aperture. 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 out of focus if light is not well converged. The border between these is sometimes defined using a " circle of confusion" criterion. A principal focus or focal point is a special focus: * For a lens, or a spherical or parabolic mirror, it is a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monochromator
A monochromator is an 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 from the Greek roots ''mono-'', "single", and ''chroma'', "colour", and the Latin suffix ''-ator'', denoting an agent. 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 below for a discussion of some of the uses of monochromators. In hard X-ray and neutron optics, crystal monochromators are used to define wave conditions on the instruments. Techniques A monochromator can use either the phenomenon of optical dispersio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diffraction
Diffraction is defined as the interference or bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacle/aperture. The diffracting object or aperture effectively becomes a secondary source of the propagating wave. Italian scientist Francesco Maria Grimaldi coined the word ''diffraction'' and was the first to record accurate observations of the phenomenon in 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 bending pattern is most pronounced when a wave from a coherent source (such as a laser) encounters a slit/aperture that is comparable in size to its wavelength, as shown in the inserted image. This is due to the addition, or interference, of different points on the wavefront (or, equivalently, each wavelet) that travel by paths of di ... [...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) 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 constituent spectral ... [...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, known for publishing 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 Prizes, National Book Awards and other merits. In 1978 the company merged with Atheneum and became The Scribner Book Companies. In turn it merged into 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 Scribner's children list was merged into Atheneum. The former imprint, no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
