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Daniel Kirkwood
Daniel Kirkwood (September 27, 1814 – June 11, 1895) was an American astronomer. Kirkwood was born in Harford County, Maryland to John and Agnes (née Hope) Kirkwood. He graduated in mathematics from the York County Academy in York, Pennsylvania in 1838. After teaching there for five years, he became Principal of the Lancaster High School in Lancaster, Pennsylvania, and after another five years he moved on to become Principal of the Pottsville Academy in Pottsville, Pennsylvania. In 1851, he was elected as a member to the American Philosophical Society. The same year he became Professor of Mathematics at Delaware College and in 1856 Professor of Mathematics at Indiana University in Bloomington, Indiana, where he stayed until his retirement in 1886, with the exception of two years, 1865–1867, at Jefferson College in Canonsburg, Pennsylvania. Kirkwood's most significant contribution came from his study of asteroid orbits. When arranging the then-growing number of discovered ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harford County, Maryland
Harford County is located in the U.S. state of Maryland. As of the 2020 census, the population was 260,924. Its county seat is Bel Air. Harford County is included in the Baltimore-Columbia-Towson, MD Metropolitan Statistical Area, which is also included in the Washington-Baltimore-Arlington, DC-MD-VA-WV-PA Combined Statistical Area. History In 1608 the area was settled by Massawomecks and Susquehannocks. The first European to see the area was John Smith in 1608 when he traveled up the Chesapeake Bay from Jamestown. In 1652, the English and Susquehannocks signed a treaty at what is now Annapolis for the area now called Harford County. Harford County was formed on March 22, 1774 from the eastern part of Baltimore County with a population of 13,000 people. On March 22, 1775, Harford County hosted the signers of the Bush Declaration, a precursor document to the American Revolution. On January 22, 1782, Bel Air became the county seat. Havre de Grace, a city incorporated i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asteroid
An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. Of the roughly one million known asteroids the greatest number are located between the orbits of Mars and Jupiter, approximately 2 to 4 AU from the Sun, in the main asteroid belt. Asteroids are generally classified to be of three types: C-type, M-type, and S-type. These were named after and are generally identified with carbonaceous, metallic, and silicaceous compositions, respectively. The size of asteroids varies greatly; the largest, Ceres, is almost across and qualifies as a dwarf planet. The total mass of all the asteroids combined is only 3% that of Earth's Moon. The majority of main belt asteroids follow slightly elliptical, stable orbits, revolving in the same direction as the Earth and taking from three to six years to co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kirkwood (crater)
Kirkwood is a well-formed lunar impact crater that is located on the far side of the Moon, on the northern hemisphere, approximately 68 kilometers in diameter. It lies just to the northeast of the crater Sommerfeld, and Hippocrates is located to the east-northeast. It was named after American astronomer Daniel Kirkwood. Description The perimeter of this crater is generally circular, with a few slight outward notches particularly to the southeast. It displays very little appearance of wear, and neither the interior nor the outer rampart are marked by any craters of note. The inner wall has slumped somewhat, and has formed a few terrace-like structures. The interior ejecta spreads a good way across the inner floor, covering nearly half the diameter. At the midpoint appear several small hills producing a central peak formation. Satellite craters By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1578 Kirkwood
1578 Kirkwood, provisional designation , is a Hilda asteroid from the outermost regions of the asteroid belt, approximately 52 kilometers in diameter. It was discovered on 10 January 1951, by astronomers of the Indiana Asteroid Program at Goethe Link Observatory in Indiana, United States. The asteroid was named after American astronomer Daniel Kirkwood. Orbit and classification ''Kirkwood'' belongs to the orbital Hilda group, which is located outermost part of the main belt. Asteroids in this dynamical group have semi-major axis between 3.7 and 4.2 AU and stay in a 3:2 resonance with the gas giant Jupiter. ''Kirkwood'', however, is a background asteroid and not a member of the (collisional) Hilda family (). It orbits the Sun at a distance of 3.0–4.9 AU once every 7 years and 9 months (2,839 days). Its orbit has an eccentricity of 0.24 and an inclination of 1 ° with respect to the ecliptic. The asteroid was first observed as at Turku Observatory in February ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Nebula
The formation of the Solar System began about 4.6 billion years ago with the gravitational collapse of a small part of a giant molecular cloud. Most of the collapsing mass collected in the center, forming the Sun, while the rest flattened into a protoplanetary disk out of which the planets, moons, asteroids, and other small Solar System bodies formed. This model, known as the nebular hypothesis, was first developed in the 18th century by Emanuel Swedenborg, Immanuel Kant, and Pierre-Simon Laplace. Its subsequent development has interwoven a variety of scientific disciplines including astronomy, chemistry, geology, physics, and planetary science. Since the dawn of the space age in the 1950s and the discovery of extrasolar planets in the 1990s, the model has been both challenged and refined to account for new observations. The Solar System has evolved considerably since its initial formation. Many moons have formed from circling discs of gas and dust around their parent pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sears Cook Walker
Sears Cook Walker (March 28, 1805 – January 30, 1853) was an American astronomer. Born at Wilmington, Massachusetts son of Benjamin Walker and Susanna Cook, he graduated from Harvard University in 1825, he was a teacher till 1835, was an actuary in 1835-1845 for the Pennsylvania Company for Insurance on Lives and Granting Annuities, and then became one of several assistants at the United States Naval Observatory following orders from Superintendent Matthew Fontaine Maury. Sears C. Walker was fired by Maury for publishing United States Naval Observatory findings on the planet Neptune in a foreign nation's scientific news through the help of Joseph Henry of the Smithsonian Institution. But it was too late and Walker got personal credit for work that he was only partially involved in. In 1847 he took charge of the longitude department of the United States Coast Survey, where he was among the first to make use of the electric telegraph for the purpose of determining the diffe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johannes Kepler
Johannes Kepler (; ; 27 December 1571 – 15 November 1630) was a German astronomer, mathematician, astrologer, natural philosopher and writer on music. He is a key figure in the 17th-century Scientific Revolution, best known for his laws of planetary motion, and his books '' Astronomia nova'', '' Harmonice Mundi'', and '' Epitome Astronomiae Copernicanae''. These works also provided one of the foundations for Newton's theory of universal gravitation. Kepler was a mathematics teacher at a seminary school in Graz, where he became an associate of Prince Hans Ulrich von Eggenberg. Later he became an assistant to the astronomer Tycho Brahe in Prague, and eventually the imperial mathematician to Emperor Rudolf II and his two successors Matthias and Ferdinand II. He also taught mathematics in Linz, and was an adviser to General Wallenstein. Additionally, he did fundamental work in the field of optics, invented an improved version of the refracting (or Keplerian) telescop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planet
A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a young protostar orbited by a protoplanetary disk. Planets grow in this disk by the gradual accumulation of material driven by gravity, a process called accretion. The Solar System has at least eight planets: the terrestrial planets Mercury, Venus, Earth and Mars, and the giant planets Jupiter, Saturn, Uranus and Neptune. These planets each rotate around an axis tilted with respect to its orbital pole. All of them possess an atmosphere, although that of Mercury is tenuous, and some share such features as ice caps, seasons, volcanism, hurricanes, tectonics, and even hydrology. Apart from Venus and Mars, the Solar System planets generate magnetic fields, and all except Venus and Mercury have natural satellites. The giant planets ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comet
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of solar radiation and the solar wind acting upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometers across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times Earth's diameter, while the tail may stretch beyond one astronomical unit. If sufficiently bright, a comet may be seen from Earth without the aid of a telescope and may subtend an arc of 30° (60 Moons) across the sky. Comets have been observed and recorded since ancient times by many cultures and religions. Comets usually have highly eccentric elliptical orbits, and they have a wide range of orbital periods, ranging from several years to potentially several ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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