NationMaster - Encyclopedia: 243 Ida

243 Ida is a Main belt asteroid that was imaged by the Galileo probe on August 28, 1993. Galileo mission member Ann Harch, while examining the delayed image downloads, discovered on February 17, 1994 that Ida had a small moon. It was given the provisory designation S/1993 (243) 1 and later named (243) 1 Dactyl. Dactyl is only 1.4 km in diameter; this was the first asteroid moon to be discovered. Some researchers believe that Dactyl formed from debris ejected from Ida by cratering, while others suggest that Ida and Dactyl formed as a pair a billion or more years ago when Ida's parent body was disrupted. Both of these hypotheses present difficulties that remain unresolved at this time. Since the discovery of Dactyl, other observations have suggested that asteroid moons are not uncommon. Johann Palisa (December 6, 1848 – May 2, 1925) was an Austrian astronomer, born in Troppau in Austrian Silesia (now in the Czech Republic). ... September 29 is the 272nd day of the year (273rd in leap years). ... 1884 is a leap year starting on Tuesday (click on link to calendar). ... The provisional designation of comets and asteroids are similar to each other: they both follow a pattern set in 1925 by the Minor Planet Center of the IAU. Historical designations At first, astronomers strove to assign symbols to the minor planets: 1 Ceres a stylized sickle 2 Pallas a lozenge... Minor planets, or planetoids are minor bodies of the solar system orbiting the sun that are larger than meteoroids (the largest of which might be taken to be around 10 meters or so across) but smaller than major planets (Mercury having a diameter of about 4880 km). ... The asteroid belt is a region of the solar system falling roughly between the planets Mars and Jupiter where the greatest concentration of asteroid orbits can be found. ... In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... October 22 is the 295th day of the year (296th in leap years) in the Gregorian Calendar, with 70 days remaining. ... 2004 is a leap year starting on Thursday of the Gregorian calendar. ... The Julian day or Julian day number (JDN) is the number of SI days that have elapsed since 12 noon Greenwich Mean Time (UT or TT) on Monday, January 1, 4713 BC in the proleptic Julian calendar 1. ... (This page refers to eccitricity in astrodynamics. ... In geometry, the semi-major axis (also semimajor axis) a applies to ellipses and hyperbolas. ... Giga (symbol: G) is a prefix in the SI system of units denoting 109, or 1 000 000 000. ... The metre is the basic unit of length in the International System of Units (SI: SystÃ¨me International dUnitÃ©s). ... The astronomical unit (AU or au or a. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ... A day is any of several different units of time. ... A Julian year is the length of an average year in the Julian calendar, 365. ... The orbital speed of a body, generally a planet, a natural satellite, an artificial satellite, or a multiple star, is the speed at which it orbits around the barycenter of a system, usually around a more massive body. ... The second (symbol s) is a unit for time, and one of seven SI base units. ... Inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit and is the angular distance of the orbital plane from the plane of the reference (usually planets equator or the ecliptic), stated in degrees. ... A degree (or in full a degree of arc), usually symbolized Â°, is a measurement of plane angle, representing 1/360 of a full rotation. ... The Longitude of the ascending node () is one of the orbital elements used to specify the orbit of an object in space. ... The argument of the perihelion is one of the orbital elements describing the orbit of a planet. ... In the study of orbital dynamics the mean anomaly is a measure of time, specific to the orbiting body p, which is a multiple of 2π radians at and only at periapsis. ... A kilometre (American spelling: kilometer, symbol: km) is a unit of length equal to 1000 metres (from the Greek words khilia = thousand and metro = count/measure). ... Mass is a property of physical objects that, roughly speaking, measures the amount of matter they contain. ... The international prototype, made of platinum-iridium, which is kept at the BIPM under conditions specified by the 1st CGPM in 1889. ... Density (symbol: Ï - Greek: rho) is a measure of mass per unit of volume. ... A cubic centimetre (cm3) is an SI derived unit of volume, equal to the volume of a cube with side length of 1 centi metre. ... It has been suggested that Law of universal gravitation be merged into this article or section. ... In physics, for a given gravitational field and a given position, the escape velocity is the minimum speed an object without propulsion, at that position, needs to have to move away indefinitely from the source of the field, as opposed to falling back or staying in an orbit within a... In astronomy, a rotation period is the time an astronomical object takes to complete one revolution around its rotation axis. ... An asteroid is a small, solid object in our Solar System, orbiting the Sun. ... Approximately 17% of all known asteroids are of an S-type (for stony) composition. ... In astronomy, absolute magnitude is the apparent magnitude, m, an object would have if it were at a standardized distance away. ... The albedo is a measure of reflectivity of a surface or body. ... Temperature is the physical property of a system which underlies the common notions of hot and cold; the material with the higher temperature is said to be hotter. ... The kelvin (symbol: K) is the SI unit of temperature, and is one of the seven SI base units. ... NASA image of 243 Ida and Dactyl. ... NASA image of 243 Ida and Dactyl. ... Image of the main asteroid belt between the orbits of Mars and Jupiter. ... An asteroid is a small, solid object in our Solar System, orbiting the Sun. ... Galileo being deployed after being launched by the Space Shuttle Atlantis on the STS-34 mission Galileo was an unmanned spacecraft sent by NASA to study the planet Jupiter and its moons. ... August 28 is the 240th day of the year in the Gregorian Calendar (241st in leap years), with 125 days remaining. ... 1993 is a common year starting on Friday of the Gregorian calendar and marked the Beginning of the International Decade to Combat Racism and Racial Discrimination (1993-2003). ... February 17 is the 48th day of the year in the Gregorian calendar. ... 1994 was a common year starting on Saturday of the Gregorian calendar, and was designated the International year of the Family. ... Moons of solar system scaled to Earths Moon The common noun moon (not capitalized) is used to mean any natural satellite of the other planets. ... 243 Ida (left) and Dacytl (right), as photographed by Galileo. ... An asteroid moon is an asteroid that orbits another asteroid. ... This article is about impact craters, also known as meteor craters. ...

It was discovered by Johann Palisa on September 29, 1884 in Vienna. Johann Palisa (December 6, 1848 – May 2, 1925) was an Austrian astronomer, born in Troppau in Austrian Silesia (now in the Czech Republic). ... September 29 is the 272nd day of the year (273rd in leap years). ... 1884 is a leap year starting on Tuesday (click on link to calendar). ... View of Vienna This article is about the city and federal state in Austria. ...

Ida is named after Ida, a Cretan nymph in Greek mythology who lived on a mountain that bore her name (see Mount Ida, Crete). Ida of Bernicia, King of a British state. ... Greece and Crete Crete, sometimes spelled Krete (Greek ÎšÏÎ®Ï„Î· / Kriti) is the largest of the Greek islands and the fifth largest in the Mediterranean Sea. ... Greek mythology comprises the collected legends of Greek gods, goddesses, heroes, and heroines, originally created and spread within an oral-poetic tradition. ...

Although Ida's dimensions, measured along the principal axes (based on its rotation) are 53.6×24.0×15.2 km, the best-fit ellipsoid measures 60.0×25.2×18.6 km. The maximum deviation from this ellipsoid remains quite large, at 8.4 km. Since its mass is accurately known thanks to its little moon, one can calculate that its surface gravity varies between 0.0031 and 0.0324 m/s² depending on one's position on its surface. The rotation axis is within one degree of the shorter dimension axis, which means the centrifugal effect can reach a value as large as 0.0042 m/s² —at the tips of its longest axes, Ida is actually under tension!

The color picture is made from images taken by the imaging system on the Galileo spacecraft about 14 minutes before its closest approach to 243 Ida on August 28, 1993. The range from the spacecraft was about 10.5 megametres (6,500 miles). The images used are from the sequence in which Ida's moon was originally discovered; the moon is visible to the right of the asteroid. This picture is made from images through the 410 nanometres (violet), 756 nm (infrared) and 968 nm (infrared) filters. The color is 'enhanced' in the sense that the CCD camera is sensitive to near infrared wavelengths of light beyond human vision; a 'natural' color picture of this asteroid would appear mostly gray. Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. ... A charge-coupled device (CCD) is a sensor for recording images, consisting of an integrated circuit containing an array of linked, or coupled, capacitors. ...

Shadings in the image indicate changes in illumination angle on the many steep slopes of this irregular body as well as subtle color variations due to differences in the physical state and composition of the soil (regolith). There are brighter areas, appearing bluish in the picture, around craters on the upper left end of Ida, around the small bright crater near the center of the asteroid, and near the upper right- hand edge (the limb). This is a combination of more reflected blue light and greater absorption of near infrared light, suggesting a difference in the abundance or composition of iron-bearing minerals in these areas. Regolith (pronounced re-go-lith) is a layer of loose, heterogeneous material covering solid rock. ...

Ida's moon also has a deeper near-infrared absorption and a different color in the violet than any area on this side of Ida. The moon is not identical in spectral properties to any area of Ida in view here, though its overall similarity in reflectance and general spectral type suggests that it is made of the same rock types basically. These data, combined with study of further imaging data and more detailed spectra from the Near Infrared Mapping Spectrometer, may allow scientists to determine whether the larger parent body of which Ida, its moon, and some other asteroids are fragments was a heated, differentiated object or made of relatively unaltered primitive chondritic material. Chondrules in the chondrite Grassland. ...

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