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Herschelian Telescope
A reflecting telescope (also called a reflector) is a telescope that uses a single or a combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century by Isaac Newton as an alternative to the refracting telescope which, at that time, was a design that suffered from severe chromatic aberration. Although reflecting telescopes produce other types of optical aberrations, it is a design that allows for very large diameter objectives. Almost all of the major telescopes used in astronomy research are reflectors. Many variant forms are in use and some employ extra optical elements to improve image quality or place the image in a mechanically advantageous position. Since reflecting telescopes use mirrors, the design is sometimes referred to as a catoptric telescope. From the time of Newton to the 1800s, the mirror itself was made of metal usually speculum metal. This type included Newton's first designs and even the largest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SOFIA 2
Sofia ( ; bg, София, Sofiya, ) is the Capital city, capital and List of cities and towns in Bulgaria, largest city of Bulgaria. It is situated in the Sofia Valley at the foot of the Vitosha mountain in the western parts of the country. The city is built west of the Iskar (river), Iskar river, and has many mineral springs, such as the Sofia Central Mineral Baths. It has a humid continental climate. Being in the centre of the Balkans, it is midway between the Black Sea and the Adriatic Sea, and closest to the Aegean Sea. Known as Serdica in Late antiquity, Antiquity and Sredets in the Middle Ages, Sofia has been an area of List of oldest continuously inhabited cities, human habitation since at least 7000 BC. The recorded history of the city begins with the attestation of the conquest of Serdica by the Roman Republic in 29 BC from the Celtic settlement of Southeast Europe, Celtic tribe Serdi. During the decline of the Roman Empire, the city was raided by Huns, Visigoths, P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
