Johann Gabriel Doppelmayr
Johann Gabriel Doppelmayr was a German mathematician and cartographer. He was born in Nuremberg, the son of the merchant Johann Siegmund Doppelmayr and he entered the Aegidien-Gymnasium in Nuremberg in 1689, the University of Altdorf in 1696. His studies included mathematics and jurisprudence, he continued his studies in Halle and graduated in 1698 with a dissertion on the Sun. During studying at the University of Halle, he learned French and he continued to study astronomy and learned to grind and figure his own telescope lenses. His career was academic, and he became professor of mathematics at the Aegidien-Gymnasium from 1704 until his death and he is not noted for any discoveries, but he did publish several works of a scientific nature. His publications covered topics on mathematics and astronomy, including sundials, spherical trigonometry, one of his works included useful biographical information on several hundred mathematicians and instrument makers of Nuremberg. Doppelmayr developed a relationship with the Dominican monk and cartographer Johann Batist Homann.
In the early 1700s, Doppelmayr prepared a number of plates that had appeared in Homanns atlases. The remaining ten plates were actual star charts, including hemispheres centered on the equatorial poles, Doppelmayr married Susanna Maria Kellner in 1716, and the couple had four children of which one survived. Doppelmayr became a member of scientific societies, most notably the Berlin Academy, the Royal Society in 1733. The crater Doppelmayer on the Moon was named after him by Johann Hieronymus Schröter in 1791, the minor planet 12622 Doppelmayr is named in his honour. The Atlas Coelestis of Johann Gabriel Doppelmayr, Atlas Coelestis, Heredi Homannianorum,1742. Full digital facsimile at Linda Hall Library, Atlas novus coelestis, Norimberga 1742 da www. atlascoelestis. com
Uranias Mirror, or, a view of the Heavens is a set of 32 astronomical star chart cards, first published in November 1824. They had illustrations based on Alexander Jamiesons A Celestial Atlas, and they were engraved by Sidney Hall, and were said to be designed by a lady, but have since been identified as the work of the Reverend Richard Rouse Bloxam, an assistant master at Rugby School. The cover of the box-set showed a depiction of Urania, the muse of astronomy, P. D. Uranias Mirror illustrates 79 constellations, some of which are now obsolete, and various subconstellations, such as Caput Medusæ. Some cards focus on a constellation, others include several, with Card 32, centered on Hydra. Card 28 has six, and no other card has more than four, each card measures 8 inches by 5 1⁄2. A book by Jehoshaphat Aspin entitled A Familiar Treatise on Astronomy was written to accompany the cards. Both the book and cards were published by Samuel Leigh,18 Strand, although the publishing firm had moved to 421 Strand.
The cards and books came within a box illustrated with a woman almost certainly intended to be Urania, hingley calls it One of the most charming and visually attractive of the many aids to astronomical self-instruction produced in the early nineteenth century. While he had several sons, he has no other known publications. The reasons for the disguise are unknown, hingley notes that many contemporary publications attempted to suggest women had played a role in their creation, perhaps to make them sound less threatening. Ian Ridpath, noting the plagiarism of the art from A Celestial Atlas, a December 1824 advertisement, which states the cards were just published, offered the cards plain at £1/8s or fully coloured for £1/14s. This first edition did not include any stars surrounding the named constellations and this was changed for the second edition, which added back stars around theose constellations. An American edition was published in 1832, modern reprints were produced in 1993, and Barnes & Noble reproduced the American edition in 2004.
The accompanying book, A Familiar Treatise on Astronomy by Jehoshaphat Aspin went through at least four editions, the second edition featured a marked expansion in content, growing from 121 pages in the first edition to 200 pages in the second. A Second Part of Uranias Mirror, which was to have included illustrations of the planets and an orrery, was advertised. Includes a video presentation of the cards
A constellation is formally defined as a region of the celestial sphere, with boundaries laid down by the International Astronomical Union. The constellation areas mostly had their origins in Western-traditional patterns of stars from which the constellations take their names, in 1922, the International Astronomical Union officially recognized the 88 modern constellations, which cover the entire sky. They began as the 48 classical Greek constellations laid down by Ptolemy in the Almagest, Constellations in the far southern sky are late 16th- and mid 18th-century constructions. 12 of the 88 constellations compose the zodiac signs, though the positions of the constellations only loosely match the dates assigned to them in astrology. The term constellation can refer to the stars within the boundaries of that constellation. Notable groupings of stars that do not form a constellation are called asterisms, when astronomers say something is “in” a given constellation they mean it is within those official boundaries.
Any given point in a coordinate system can unambiguously be assigned to a single constellation. Many astronomical naming systems give the constellation in which an object is found along with a designation in order to convey a rough idea in which part of the sky it is located. For example, the Flamsteed designation for bright stars consists of a number, the word constellation seems to come from the Late Latin term cōnstellātiō, which can be translated as set of stars, and came into use in English during the 14th century. It denotes 88 named groups of stars in the shape of stellar-patterns, the Ancient Greek word for constellation was ἄστρον. Colloquial usage does not draw a distinction between constellation in the sense of an asterism and constellation in the sense of an area surrounding an asterism. The modern system of constellations used in astronomy employs the latter concept, the term circumpolar constellation is used for any constellation that, from a particular latitude on Earth, never sets below the horizon.
From the North Pole or South Pole, all constellations south or north of the equator are circumpolar constellations. In the equatorial or temperate latitudes, the term equatorial constellation has sometimes been used for constellations that lie to the opposite the circumpolar constellations. They generally include all constellations that intersect the celestial equator or part of the zodiac, usually the only thing the stars in a constellation have in common is that they appear near each other in the sky when viewed from the Earth. In galactic space, the stars of a constellation usually lie at a variety of distances, since stars travel on their own orbits through the Milky Way, the star patterns of the constellations change slowly over time. After tens to hundreds of thousands of years, their familiar outlines will become unrecognisable, the terms chosen for the constellation themselves, together with the appearance of a constellation, may reveal where and when its constellation makers lived.
The earliest direct evidence for the constellations comes from inscribed stones and it seems that the bulk of the Mesopotamian constellations were created within a relatively short interval from around 1300 to 1000 BC
Hydra is the largest of the 88 modern constellations, measuring 1303 square degrees. Also one of the longest at over 100 degrees, its southern end abuts Libra and Centaurus and it has a long history, having been included among the 48 constellations listed by the 2nd century astronomer Ptolemy. It is commonly represented as a water snake and it should not be confused with the similarly named constellation of Hydrus. The Greek constellation of Hydra is an adaptation of a Babylonian constellation and it is one of two Babylonian serpent constellations, a mythological hybrid of serpent and bird. The shape of Hydra resembles a snake, and features as such in some Greek myths. One myth associates it with a snake that a crow served Apollo in a cup when it was sent to fetch water, Apollo saw through the fraud, and angrily cast the crow, cup. It is associated with the monster Hydra, with its heads, killed by Hercules. According to legend, if one of the heads was cut off. However, Hercules burned out the roots of the heads he severed to prevent them from growing again, in Hindu Mythology the star that equivalents Hydra is Ashlesha.
In Chinese astronomy, the stars that correspond to Hydra are located within the Vermilion Bird, in Japanese culture, the stars are known as Nuriko. Despite its size, Hydra contains only one reasonably bright star, Alphard and it is an orange giant of magnitude 2.0,177 light-years from Earth. Its traditional name means the solitary one, beta Hydrae is a blue-white star of magnitude 4.3,365 light-years from Earth. Gamma Hydrae is a giant of magnitude 3.0,132 light-years from Earth. Hydra has one bright binary star, Epsilon Hydrae, which is difficult to split in amateur telescopes, the primary is a yellow star of magnitude 3.4 and the secondary is a blue star of magnitude 6.7. However, there are several double stars and binary stars in Hydra. 27 Hydrae is a star with two components visible in binoculars and three visible in small amateur telescopes. The primary is a star of magnitude 4.8,244 light-years from Earth. The secondary, a star, appears in binoculars at magnitude 7.0 but is composed of a magnitude 7
A chemical element or element is a species of atoms having the same number of protons in their atomic nuclei. There are 118 elements that have identified, of which the first 94 occur naturally on Earth with the remaining 24 being synthetic elements. There are 80 elements that have at least one stable isotope and 38 that have exclusively radioactive isotopes, iron is the most abundant element making up Earth, while oxygen is the most common element in the Earths crust. Chemical elements constitute all of the matter of the universe. The two lightest elements and helium, were formed in the Big Bang and are the most common elements in the universe. The next three elements were formed mostly by cosmic ray spallation, and are rarer than those that follow. Formation of elements with from 6 to 26 protons occurred and continues to occur in main sequence stars via stellar nucleosynthesis, the high abundance of oxygen and iron on Earth reflects their common production in such stars. The term element is used for atoms with a number of protons as well as for a pure chemical substance consisting of a single element. A single element can form multiple substances differing in their structure, when different elements are chemically combined, with the atoms held together by chemical bonds, they form chemical compounds.
Only a minority of elements are found uncombined as relatively pure minerals, among the more common of such native elements are copper, gold and sulfur. All but a few of the most inert elements, such as gases and noble metals, are usually found on Earth in chemically combined form. While about 32 of the elements occur on Earth in native uncombined forms. For example, atmospheric air is primarily a mixture of nitrogen and argon, the history of the discovery and use of the elements began with primitive human societies that found native elements like carbon, sulfur and gold. Later civilizations extracted elemental copper, tin and iron from their ores by smelting, using charcoal and chemists subsequently identified many more, almost all of the naturally occurring elements were known by 1900. Save for unstable radioactive elements with short half-lives, all of the elements are available industrially, almost all other elements found in nature were made by various natural methods of nucleosynthesis.
On Earth, small amounts of new atoms are produced in nucleogenic reactions, or in cosmogenic processes. Of the 94 naturally occurring elements, those with atomic numbers 1 through 82 each have at least one stable isotope, Isotopes considered stable are those for which no radioactive decay has yet been observed. Elements with atomic numbers 83 through 94 are unstable to the point that radioactive decay of all isotopes can be detected, the very heaviest elements undergo radioactive decay with half-lives so short that they are not found in nature and must be synthesized
In astronomy, declination is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declinations angle is measured north or south of the celestial equator, the root of the word declination means a bending away or a bending down. It comes from the root as the words incline and recline. Declination in astronomy is comparable to geographic latitude, projected onto the celestial sphere, points north of the celestial equator have positive declinations, while those south have negative declinations. Any units of measure can be used for declination, but it is customarily measured in the degrees, minutes. Declinations with magnitudes greater than 90° do not occur, because the poles are the northernmost and southernmost points of the celestial sphere, the Earths axis rotates slowly westward about the poles of the ecliptic, completing one circuit in about 26,000 years. This effect, known as precession, causes the coordinates of stationary celestial objects to change continuously, equatorial coordinates are inherently relative to the year of their observation, and astronomers specify them with reference to a particular year, known as an epoch.
Coordinates from different epochs must be rotated to match each other. The currently used standard epoch is J2000.0, which is January 1,2000 at 12,00 TT, the prefix J indicates that it is a Julian epoch. Prior to J2000.0, astronomers used the successive Besselian Epochs B1875.0, B1900.0, the declinations of Solar System objects change very rapidly compared to those of stars, due to orbital motion and close proximity. This similarly occurs in the Southern Hemisphere for objects with less than −90° − φ. An extreme example is the star which has a declination near to +90°. Circumpolar stars never dip below the horizon, there are other stars that never rise above the horizon, as seen from any given point on the Earths surface. Generally, if a star whose declination is δ is circumpolar for some observer, a star whose declination is −δ never rises above the horizon, as seen by the same observer. Likewise, if a star is circumpolar for an observer at latitude φ, neglecting atmospheric refraction, declination is always 0° at east and west points of the horizon.
At the north point, it is 90° − |φ|, and at the south point, from the poles, declination is uniform around the entire horizon, approximately 0°. Non-circumpolar stars are visible only during certain days or seasons of the year, the Suns declination varies with the seasons. As seen from arctic or antarctic latitudes, the Sun is circumpolar near the summer solstice, leading to the phenomenon of it being above the horizon at midnight
Hydrogen is a chemical element with chemical symbol H and atomic number 1. With a standard weight of circa 1.008, hydrogen is the lightest element on the periodic table. Its monatomic form is the most abundant chemical substance in the Universe, non-remnant stars are mainly composed of hydrogen in the plasma state. The most common isotope of hydrogen, termed protium, has one proton, the universal emergence of atomic hydrogen first occurred during the recombination epoch. At standard temperature and pressure, hydrogen is a colorless, tasteless, non-toxic, since hydrogen readily forms covalent compounds with most nonmetallic elements, most of the hydrogen on Earth exists in molecular forms such as water or organic compounds. Hydrogen plays an important role in acid–base reactions because most acid-base reactions involve the exchange of protons between soluble molecules. In ionic compounds, hydrogen can take the form of a charge when it is known as a hydride. The hydrogen cation is written as though composed of a bare proton, Hydrogen gas was first artificially produced in the early 16th century by the reaction of acids on metals.
Industrial production is mainly from steam reforming natural gas, and less often from more energy-intensive methods such as the electrolysis of water. Most hydrogen is used near the site of its production, the two largest uses being fossil fuel processing and ammonia production, mostly for the fertilizer market, Hydrogen is a concern in metallurgy as it can embrittle many metals, complicating the design of pipelines and storage tanks. Hydrogen gas is flammable and will burn in air at a very wide range of concentrations between 4% and 75% by volume. The enthalpy of combustion is −286 kJ/mol,2 H2 + O2 →2 H2O +572 kJ Hydrogen gas forms explosive mixtures with air in concentrations from 4–74%, the explosive reactions may be triggered by spark, heat, or sunlight. The hydrogen autoignition temperature, the temperature of spontaneous ignition in air, is 500 °C, the detection of a burning hydrogen leak may require a flame detector, such leaks can be very dangerous. Hydrogen flames in other conditions are blue, resembling blue natural gas flames, the destruction of the Hindenburg airship was a notorious example of hydrogen combustion and the cause is still debated.
The visible orange flames in that incident were the result of a mixture of hydrogen to oxygen combined with carbon compounds from the airship skin. H2 reacts with every oxidizing element, the ground state energy level of the electron in a hydrogen atom is −13.6 eV, which is equivalent to an ultraviolet photon of roughly 91 nm wavelength. The energy levels of hydrogen can be calculated fairly accurately using the Bohr model of the atom, the atomic electron and proton are held together by electromagnetic force, while planets and celestial objects are held by gravity. The most complicated treatments allow for the effects of special relativity
Johannes Hevelius was a councillor and mayor of Danzig, part of the Polish-Lithuanian Commonwealth. As an astronomer he gained a reputation as the founder of lunar topography and described ten new constellations, Hevelius father was Abraham Hewelke, his mother Kordula Hecker. They were German-speaking Lutherans, wealthy brewing merchants of Bohemian origin, as a young boy, Hevelius was sent to Gądecz where he studied the Polish language. Hevelius brewed the famous Jopen beer, which gave its name to the Jopengasse/Jopejska Street, after 1945 renamed as Piwna Street. In 1634 he settled in his town, and on 21 March 1635 married Katharine Rebeschke. The following year, Hevelius became a member of the beer-brewing guild, throughout his life, Hevelius took a leading part in municipal administration, becoming town councillor in 1651, but from 1639 on, his chief interest was astronomy. This may have been the longest tubed telescope before the advent of the tubeless aerial telescope, the observatory was known by the name Sternenburg or Star Castle This private observatory was visited by Polish Queen Marie Louise Gonzaga on 29 January 1660.
While the noble status was not ratified by the Polish Sejm Heveliuss coat of arms includes the distinctive Polish royal crown, in May 1679 the young Englishman Edmond Halley visited him as emissary of the Royal Society, whose fellow Hevelius had been since 1664. The Royal Society considers him one of the first German fellows, małgorzata Czerniakowska writes that Jan Heweliusz was the first Pole to be inducted into the Royal Society in London. This important event took place on 19th March 1664 and he is thus considered the last astronomer to do major work without the use of a telescope. He discovered four comets, in 1652,1661,1672 and 1677 and these discoveries led to his thesis that such bodies revolve around the Sun in parabolic paths. A complex halo phenomenon was observed by many in the city on 20 February 1661, his first wife, died in 1662, and a year Hevelius married Elisabeth Hevelius née Koopmann, the young daughter of a merchant family. Elisabeth supported him, published two of his works after his death, and is considered the first female astronomer and his observatory and books were destroyed by fire on 26 September 1679.
The catastrophe is described in the preface to his Annus climactericus and he promptly repaired the damage enough to enable him to observe the great comet of December 1680. He named the constellation Sextans in memory of these lost instruments and this constellation first occurred publicly in his star atlas Firmamentum Sobiescianum, that was printed in his own house at lavish expense, and he himself engraved many of the printing plates. His health had suffered from the shock of the 1679 fire, Hevelius was buried in St. Catherines Church in his hometown. Descendants of Hevelius live in Urzędów in Poland where they support local astronomy enthusiasts, Hevelius description of his naked eye observation method in the first part of this work led to a dispute with Robert Hooke who claimed observations without telescopic sights were of little value. Obsolete, Mons Maenalus, and Triangulum Minus
In observational astronomy, a double star or visual double is a pair of stars that appear close to each other in the sky as seen from Earth when viewed through an optical telescope. Multiple stars are studied in this way, although the dynamics of multiple stellar systems are more complex than those of binary stars. There are three types of paired stars, Optical Doubles are unrelated stars that appear close together through chance alignment with Earth, visual Binaries are gravitationally-bound stars that are separately visible with a telescope. Non-Visual Binaries are stars whose binary status was deduced through more esoteric means, such as occultation, improvements in telescopes can shift previously non-visual binaries into visual binaries, as happened with Polaris A in 2006. It is only the inability to observe two separate stars that distinguish non-visual and visual binaries. Mizar, in Ursa Major, was observed to be double by Benedetto Castelli, since that time, the search has been carried out thoroughly and the entire sky has been examined for double stars down to a limiting apparent magnitude of about 9.0.
At least 1 in 18 stars brighter than 9.0 magnitude in the half of the sky are known to be double stars visible with a 36-inch telescope. The unrelated categories of optical doubles and true binaries are lumped together for historical and practical reasons, when Mizar was found to be a binary, it was quite difficult to determine whether a double star was a binary system or only an optical double. Improved telescopes and photography are the tools used to make the distinction. After it was determined to be a binary, Mizars components were found to be spectroscopic binaries themselves. Observation of visual double stars by visual measurement will yield the separation, or angular distance, the position angle specifies the direction in which the stars are separated and is defined as the bearing from the brighter component to the fainter, where north is 0°. In the measures of a binary, the position angle will change progressively. Plotting the measures in the plane will produce an ellipse and this is the apparent orbit, the projection of the orbit of the two stars onto the celestial sphere, the true orbit can be computed from it.
Although it is expected that the majority of catalogued visual doubles are visual binaries, visual double stars may be distinguished from binary stars by observing their relative motion. Some bright visual double stars have a Bayer designation, in this case, the components may be denoted by superscripts. An example of this is α Crucis, whose components are α1 Crucis, since α1 Crucis is a spectroscopic binary, this is actually a multiple star. Superscripts are used to more distant, physically unrelated, pairs of stars with the same Bayer designation, such as α1,2 Capricorni, ξ1,2 Centauri. These optical pairs are resolvable by the naked eye, apart from these pairs, the components of a double star are generally denoted by the letters A and B appended to the designation, of whatever sort, of the double star
Leo /ˈliːoʊ/ is one of the constellations of the zodiac, lying between Cancer the crab to the west and Virgo the maiden to the east. Its name is Latin for lion, and to the ancient Greeks represented the Nemean Lion killed by the mythical Greek hero Heracles as one of his twelve labors. The lions mane and shoulders form an asterism known as The Sickle, Leo contains many bright stars, many of which were individually identified by the ancients. It is a double star divisible in binoculars, with a secondary of magnitude 7.7 and its traditional name means the little king. Beta Leonis, called Denebola, is at the end of the constellation to Regulus. It is a star of magnitude 2.23,36 light-years from Earth. The name Denebola means the lions tail, Gamma Leonis, is a binary star with a third optical component, the primary and secondary are divisible in small telescopes and the tertiary is visible in binoculars. The primary is a giant star of magnitude 2.61. The unrelated tertiary,40 Leonis, is a star of magnitude 4.8.
Its traditional name, means the forehead, Delta Leonis, called Zosma, is a blue-white star of magnitude 2.58,58 light-years from Earth. Epsilon Leonis is a giant of magnitude 3.0,251 light-years from Earth. Zeta Leonis, called Adhafera, is a triple star. The brightest and only star designated Zeta Leonis, is a giant star of magnitude 3.65,260 light-years from Earth. The second brightest,39 Leonis, is widely spaced to the south,35 Leonis is to the north and of magnitude 6.0. Iota Leonis is a binary star divisible in amateur telescopes. To the unaided eye, Iota Leonis appears to be a star of magnitude 4.0. The system,79 light-years from Earth, has components of magnitude 4.1 and 6.7 with a period of 183 years, tau Leonis is a double star visible in binoculars. The primary is a giant of magnitude 5.0,621 light-years from Earth