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Quizlet was founded in October 2005 by Andrew Sutherland, who at the time was a 15-year old student, [2] and released to the public in January 2007. [3] Quizlet's primary products include digital flash cards , matching games , practice electronic assessments , and live quizzes.
Teach Yourself Arabic, first published in 1943, was written by Arthur Stanley Tritton. Tritton wrote a number of books on Islam and its history, and from 1938 to 1946 was Professor of Arabic at the School of Oriental and African Studies. [11] Teach Yourself Astronomy was written by the noted British astronomer David Stanley Evans in 1957.
A Question and Answer Guide to Astronomy is a book about astronomy and cosmology, and is intended for a general audience. The book was written by Pierre-Yves Bely, Carol Christian, and Jean-Rene Roy, and published in English by Cambridge University Press in 2010. It was originally written in French. [1]
Astrophotography, also known as astronomical imaging, is the photography or imaging of astronomical objects, celestial events, or areas of the night sky. The first photograph of an astronomical object (the Moon ) was taken in 1839 [ 1 ] , but it was not until the late 19th century that advances in technology allowed for detailed stellar ...
A-type star In the Harvard spectral classification system, a class of main-sequence star having spectra dominated by Balmer absorption lines of hydrogen. Stars of spectral class A are typically blue-white or white in color, measure between 1.4 and 2.1 times the mass of the Sun, and have surface temperatures of 7,600–10,000 kelvin.
Visible-light astronomy has existed as long as people have been looking up at the night sky, although it has since improved in its observational capabilities since the invention of the telescope, which is commonly credited to Hans Lippershey, a German-Dutch spectacle-maker, [1] although Galileo played a large role in the development and ...
In astronomy, seeing is the degradation of the image of an astronomical object due to turbulence in the atmosphere of Earth that may become visible as blurring, twinkling or variable distortion. The origin of this effect is rapidly changing variations of the optical refractive index along the light path from the object to the detector.
Vera Florence Cooper Rubin (/ ˈ r uː b ɪ n /; July 23, 1928 – December 25, 2016) was an American astronomer who pioneered work on galaxy rotation rates. [1] [2] She uncovered the discrepancy between the predicted and observed angular motion of galaxies by studying galactic rotation curves.