|
Transit Of Venus
frameless, upright=0.5 A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and a superior planet, becoming visible against (and hence obscuring a small portion of) the solar disk. During a transit, Venus can be seen from Earth as a small black dot moving across the face of the Sun. The duration of such transits is usually several hours (the transit of 2012 lasted 6 hours and 40 minutes). A transit is similar to a solar eclipse by the Moon. While the diameter of Venus is more than three times that of the Moon, Venus appears smaller, and travels more slowly across the face of the Sun, because it is much farther away from Earth. Transits of Venus are among the rarest of predictable astronomical phenomena. They occur in a pattern that generally repeats every 243 years, with pairs of transits eight years apart separated by long gaps of 121.5 years and 105.5 years. The periodicity is a reflection of the fact that the orbital period ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transit Of Venus, 2012
The 2012 transit of Venus, when the planet Venus appeared as a small, dark spot passing across the face of the Sun, began at 22:09 UTC on 5 June 2012, and finished at 04:49 UTC on 6 June. Depending on the position of the observer, the exact times varied by up to ±7 minutes. Transit of Venus, Transits of Venus are among the rarest of predictable celestial phenomena and occur in pairs. Consecutive transits per pair are spaced 8 years apart, and consecutive pairs occur more than a century apart: The Transit of Venus, 2004, previous transit of Venus took place on 8 June 2004 (preceded by transits on 9 December 1874 and 6 December 1882); the next pair of transits will occur on 10–11 December 2117 and December 2125 within the 22nd century. Observations of the event The entire transit was visible from the western Pacific Ocean, northwesternmost North America, northeastern Asia, Japan, the Philippines, eastern Australia, New Zealand, and high Arctic locations including northernmos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Planetary Society
The Planetary Society is an American internationally-active non-governmental nonprofit organization. It is involved in research, public outreach, and political space advocacy for engineering projects related to astronomy, planetary science, and space exploration. It was founded in 1980 by Carl Sagan, Bruce Murray, and Louis Friedman, and has about 60,000 members from more than 100 countries around the world. The Society is dedicated to the exploration of the Solar System, the search for near-Earth objects, and the search for extraterrestrial life. The society's mission is stated as: "Empowering the world’s citizens to advance space science and exploration." The Planetary Society is a strong advocate for space funding and missions of exploration within NASA. They lobby Congress and engage their membership in the United States to write and call their representatives in support of NASA funding. In addition to public outreach, The Planetary Society has sponsored solar sail ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sidereal Year
A sidereal year (, ; ), also called a sidereal orbital period, is the time that Earth or another planetary body takes to orbit the Sun once with respect to the fixed stars. Hence, for Earth, it is also the time taken for the Sun to return to the same position relative to Earth with respect to the fixed stars after apparently travelling once around the ecliptic. It equals for the J2000.0 epoch. The sidereal year differs from the solar year, "the period of time required for the ecliptic longitude of the Sun to increase 360 degrees", due to the precession of the equinoxes. The sidereal year is 20 min 24.5 s longer than the mean tropical year at J2000.0 . At present, the rate of axial precession corresponds to a period of 25,772 years, so sidereal year is longer than tropical year by 1,224.5 seconds (20 min 24.5 s, ~365.24219*86400/25772). Before the discovery of the precession of the equinoxes by Hipparchus in the Hellenistic period, the difference between sidere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angular Diameter
The angular diameter, angular size, apparent diameter, or apparent size is an angular distance describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the visual angle, and in optics, it is the angular aperture (of a lens). The angular diameter can alternatively be thought of as the angular displacement through which an eye or camera must rotate to look from one side of an apparent circle to the opposite side. Humans can resolve with their naked eyes diameters of up to about 1 arcminute (approximately 0.017° or 0.0003 radians). This corresponds to 0.3 m at a 1 km distance, or to perceiving Venus as a disk under optimal conditions. Formula The angular diameter of a circle whose plane is perpendicular to the displacement vector between the point of view and the center of said circle can be calculated using the formula :\delta = 2\arctan \left(\frac\right), in which \delta is the angular diameter, and d is t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecliptic
The ecliptic or ecliptic plane is the orbital plane of the Earth around the Sun. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic against the background of stars. The ecliptic is an important reference plane and is the basis of the ecliptic coordinate system. Sun's apparent motion The ecliptic is the apparent path of the Sun throughout the course of a year. Because Earth takes one year to orbit the Sun, the apparent position of the Sun takes one year to make a complete circuit of the ecliptic. With slightly more than 365 days in one year, the Sun moves a little less than 1° eastward every day. This small difference in the Sun's position against the stars causes any particular spot on Earth's surface to catch up with (and stand directly north or south of) the Sun about four minutes later each day than it would if Earth did not orbit; a day on Earth is therefore 24 hours ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inferior Conjunction
In astronomy, a conjunction occurs when two astronomical objects or spacecraft have either the same right ascension or the same ecliptic longitude, usually as observed from Earth. When two objects always appear close to the ecliptic—such as two planets, the Moon and a planet, or the Sun and a planet—this fact implies an apparent close approach between the objects as seen in the sky. A related word, ''appulse'', is the minimum apparent separation in the sky of two astronomical objects. Conjunctions involve either two objects in the Solar System or one object in the Solar System and a more distant object, such as a star. A conjunction is an apparent phenomenon caused by the observer's perspective: the two objects involved are not actually close to one another in space. Conjunctions between two bright objects close to the ecliptic, such as two bright planets, can be seen with the naked eye. The astronomical symbol for conjunction is (Unicode U+260C ☌). The conjunction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transit Diagram Angles
Transit may refer to: Arts and entertainment Film * ''Transit'' (1979 film), a 1979 Israeli film * ''Transit'' (2005 film), a film produced by MTV and Staying-Alive about four people in countries in the world * ''Transit'' (2006 film), a 2006 film about Russian and American pilots in World War II * ''Transit'' (2012 film), an American thriller * ''Transit'' (2013 film), a Filipino independent film * ''Transit'' (2018 film), a German film Literature * ''Transit'' (Cooper novel), a 1964 science fiction by Edmund Cooper * ''Transit'' (Seghers novel), a 1944 novel by Anna Seghers * ''Transit'' (Aaronovitch novel), a 1992 novel by Ben Aaronovitch based on the TV series ''Doctor Who'' Music * Transit (band), an American emo band from Boston, Massachusetts * ''Transit'' (Ira Stein and Russel Walder album), an album by acoustic duo Ira Stein and Russel Walder, released 1986 * ''Transit'' (Sponge Cola album) * ''Transit'' (A. J. Croce album) * ''Transit T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exoplanet
An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, initially detected in 1988, was confirmed in 2003. There are many methods of detecting exoplanets. Transit photometry and Doppler spectroscopy have found the most, but these methods suffer from a clear observational bias favoring the detection of planets near the star; thus, 85% of the exoplanets detected are inside the tidal locking zone. In several cases, multiple planets have been observed around a star. About 1 in 5 Sun-like starsFor the purpose of this 1 in 5 statistic, "Sun-like" means G-type star. Data for Sun-like stars was not available so this statistic is an extrapolation from data about K-type stars. have an "Earth-sized"For the purpose of this 1 in 5 statistic, Earth-sized means 1–2 Earth radii. planet in the habitable z ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby objects show a larger parallax than farther objects when observed from different positions, so parallax can be used to determine distances. To measure large distances, such as the distance of a planet or a star from Earth, astronomers use the principle of parallax. Here, the term ''parallax'' is the semi-angle of inclination between two sight-lines to the star, as observed when Earth is on opposite sides of the Sun in its orbit. These distances form the lowest rung of what is called "the cosmic distance ladder", the first in a succession of methods by which astronomers determine the distances to celestial objects, serving as a basis for other distance measurements in astronomy forming the higher rungs of the ladder. Parallax also affects optic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1639 Transit Of Venus
The first known observations and recording of a transit of Venus were made in 1639 by the English astronomers Jeremiah Horrocks and his friend and correspondent William Crabtree. The pair made their observations independently on 4 December that year (24 November under the Julian calendar then used in England); Horrocks from Carr House, then in the village of Much Hoole, Lancashire, and Crabtree from his home in Broughton, near Manchester. The friends, followers of the new astronomy of Johannes Kepler, were self-taught mathematical astronomers who had worked methodically to correct and improve Kepler's Rudolphine tables by mere observation and measurement. In 1639, Horrocks was the only astronomer to realise that a transit of Venus was imminent; others became aware of it only after the event when Horrocks's report of it was circulated. Although the friends both died within five years of making their observations, their ground-breaking work was influential in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar System
The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar System" and "solar system" structures in theinaming guidelines document. The name is commonly rendered in lower case ('solar system'), as, for example, in the ''Oxford English Dictionary'' an''Merriam-Webster's 11th Collegiate Dictionary''. is the gravitationally bound system of the Sun and the objects that orbit it. It formed 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. The vast majority (99.86%) of the system's mass is in the Sun, with most of the remaining mass contained in the planet Jupiter. The four inner system planets— Mercury, Venus, Earth and Mars—are terrestrial planets, being composed primarily of rock and metal. The four giant planets of the outer system are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1882 Transit Of Venus
The 1882 transit of Venus, which took place on 6 December 1882 (13:57 to 20:15 UTC), was the second and last transit of Venus of the 19th century, the first having taken place eight years earlier in 1874. Many an expedition was sent by European powers to describe both episodes, eight of them alone were approved and financed in 1882 by the United States Congress. Edward James Stone organized the British expeditions sent to observe the transit. Stephen Joseph Perry and Commander Pelham Aldrich, as captain of HMS , observed the transit from an improvised tent observatory in Madagascar. Jean-Charles Houzeau invented in 1871 a heliometer with unequal focal lengths. For the observation of the transit he organized two expeditions: one to San Antonio, Texas, and another to Santiago de Chile. The two expeditions each had an identical copy of Houzeau's heliometer. The French Academy of Sciences organized ten expeditions to various locations, including Florida, Mexico, Haiti, Martin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
