|
Metis (moon)
Metis , also known as , is the innermost known moon of Jupiter. It was discovered in 1979 in images taken by ''Voyager 1'', and was named in 1983 after the first wife of Zeus, Metis. Additional observations made between early 1996 and September 2003 by the ''Galileo'' spacecraft allowed its surface to be imaged. Metis is tidally locked to Jupiter, and its shape is strongly asymmetrical, with one of the diameters being almost twice as large as the smallest one. It is also one of the two moons known to orbit Jupiter in less than the length of Jupiter's day, the other being Adrastea. It orbits within the main ring of Jupiter, and is thought to be a major contributor of material to the rings. Discovery and observations Metis was discovered in 1979 by Stephen P. Synnott in images taken by the ''Voyager 1'' probe and was provisionally designated as . In 1983, it was officially named after the mythological Metis, a Titaness who was the first wife of Zeus (the Greek equival ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galileo (spacecraft)
''Galileo'' was an American robotic space probe that studied the planet Jupiter and its moons, as well as the asteroids Gaspra and Ida. Named after the Italian astronomer Galileo Galilei, it consisted of an orbiter and an entry probe. It was delivered into Earth orbit on October 18, 1989, by , during STS-34. ''Galileo'' arrived at Jupiter on December 7, 1995, after gravitational assist flybys of Venus and Earth, and became the first spacecraft to orbit an outer planet. The Jet Propulsion Laboratory built the ''Galileo'' spacecraft and managed the ''Galileo'' program for NASA. West Germany Messerschmitt-Bölkow-Blohm supplied the propulsion module. NASA's Ames Research Center managed the atmospheric probe, which was built by Hughes Aircraft Company. At launch, the orbiter and probe together had a mass of and stood tall. Spacecraft are normally stabilized either by spinning around a fixed axis or by maintaining a fixed orientation with reference to the Sun and a star. '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Provisional Designation
Provisional designation in astronomy is the naming convention applied to astronomical objects immediately following their discovery. The provisional designation is usually superseded by a permanent designation once a reliable orbit has been calculated. Approximately 47% of the more than 1,100,000 known minor planets remain provisionally designated, as hundreds of thousands have been discovered in the last two decades. __TOC__ Minor planets The current system of provisional designation of minor planets (asteroids, centaurs and trans-Neptunian objects) has been in place since 1925. It superseded several previous conventions, each of which was in turn rendered obsolete by the increasing numbers of minor planet discoveries. A modern or new-style provisional designation consists of the year of discovery, followed by two letters and, possibly, a suffixed number. New-style provisional designation For example, the provisional designation stands for the 3910th body identified du ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synchronous Orbit
A synchronous orbit is an orbit in which an orbiting body (usually a satellite) has a period equal to the average rotational period of the body being orbited (usually a planet), and in the same direction of rotation as that body. Simplified meaning A synchronous orbit is an orbit in which the orbiting object (for example, an artificial satellite or a moon) takes the same amount of time to complete an orbit as it takes the object it is orbiting to rotate once. Properties A satellite in a synchronous orbit that is both equatorial and circular will appear to be suspended motionless above a point on the orbited planet's equator. For synchronous satellites orbiting Earth, this is also known as a geostationary orbit. However, a synchronous orbit need not be equatorial; nor circular. A body in a non-equatorial synchronous orbit will appear to oscillate north and south above a point on the planet's equator, whereas a body in an elliptical orbit will appear to oscillate eastward and west ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tidal Locking
Tidal locking between a pair of co-orbiting astronomical bodies occurs when one of the objects reaches a state where there is no longer any net change in its rotation rate over the course of a complete orbit. In the case where a tidally locked body possesses synchronous rotation, the object takes just as long to rotate around its own axis as it does to revolve around its partner. For example, the same side of the Moon always faces the Earth, although there is some variability because the Moon's orbit is not perfectly circular. Usually, only the satellite is tidally locked to the larger body. However, if both the difference in mass between the two bodies and the distance between them are relatively small, each may be tidally locked to the other; this is the case for Pluto and Charon. Alternative names for the tidal locking process are gravitational locking, captured rotation, and spin–orbit locking. The effect arises between two bodies when their gravitational interaction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inclination
Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a Plane of reference, reference plane and the orbital plane or Axis of rotation, axis of direction of the orbiting object. For a satellite orbiting the Earth directly above the Equator, the plane of the satellite's orbit is the same as the Earth's equatorial plane, and the satellite's orbital inclination is 0°. The general case for a circular orbit is that it is tilted, spending half an orbit over the northern hemisphere and half over the southern. If the orbit swung between 20° north latitude and 20° south latitude, then its orbital inclination would be 20°. Orbits The inclination is one of the six orbital elements describing the shape and orientation of a celestial orbit. It is the angle between the orbital plane and the plane of reference, normally stated in degree (angle), degrees. For a satellite orbiting a planet, the plane of reference is usually ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Eccentricity
In astrodynamics, the orbital eccentricity of an astronomical object is a dimensionless parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is a circular orbit, values between 0 and 1 form an elliptic orbit, 1 is a parabolic escape orbit (or capture orbit), and greater than 1 is a hyperbola. The term derives its name from the parameters of conic sections, as every Kepler orbit is a conic section. It is normally used for the isolated two-body problem, but extensions exist for objects following a rosette orbit through the Galaxy. Definition In a two-body problem with inverse-square-law force, every orbit is a Kepler orbit. The eccentricity of this Kepler orbit is a non-negative number that defines its shape. The eccentricity may take the following values: * circular orbit: ''e'' = 0 * elliptic orbit: 0 < ''e'' < 1 * |
Sphere
A sphere () is a Geometry, geometrical object that is a solid geometry, three-dimensional analogue to a two-dimensional circle. A sphere is the Locus (mathematics), set of points that are all at the same distance from a given point in three-dimensional space.. That given point is the centre (geometry), centre of the sphere, and is the sphere's radius. The earliest known mentions of spheres appear in the work of the Greek mathematics, ancient Greek mathematicians. The sphere is a fundamental object in many fields of mathematics. Spheres and nearly-spherical shapes also appear in nature and industry. Bubble (physics), Bubbles such as soap bubbles take a spherical shape in equilibrium. spherical Earth, The Earth is often approximated as a sphere in geography, and the celestial sphere is an important concept in astronomy. Manufactured items including pressure vessels and most curved mirrors and lenses are based on spheres. Spheres rolling, roll smoothly in any direction, so mos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porosity
Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure the "accessible void", the total amount of void space accessible from the surface (cf. closed-cell foam). There are many ways to test porosity in a substance or part, such as industrial CT scanning. The term porosity is used in multiple fields including pharmaceutics, ceramics, metallurgy, materials, manufacturing, petrophysics, hydrology, earth sciences, soil mechanics, and engineering. Void fraction in two-phase flow In gas-liquid two-phase flow, the void fraction is defined as the fraction of the flow-channel volume that is occupied by the gas phase or, alternatively, as the fraction of the cross-sectional area of the channel that is occupied by the gas phase. Void fraction usually varies from location to location in the fl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amalthea (moon)
Amalthea is a moon of Jupiter. It has the third closest orbit around Jupiter among known moons and was the fifth moon of Jupiter to be discovered, so it is also known as . It is also the fifth largest moon of Jupiter, after the four Galilean Moons. Edward Emerson Barnard discovered the moon on 9 September 1892 and named it after Amalthea of Greek mythology. It was the last natural satellite to be discovered by direct visual observation; all later moons were discovered by photographic or digital imaging. Amalthea is in a close orbit around Jupiter and is within the outer edge of the Amalthea Gossamer Ring which is formed from dust ejected from its surface. Jupiter would appear 46.5 degrees in diameter from its surface. Amalthea is the largest of the inner satellites of Jupiter and is irregularly shaped and reddish in color. It is thought to consist of porous water ice with unknown amounts of other materials. Its surface features include large craters and ridges. Close range ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inner Satellites Of Jupiter
There are 82 known moons of Jupiter, not counting a number of moonlets likely shed from the inner moons. All together, they form a satellite system which is called the Jovian system. The most massive of the moons are the four Galilean moons: Io, Europa, Ganymede, and Callisto, which were independently discovered in 1610 by Galileo Galilei and Simon Marius and were the first objects found to orbit a body that was neither Earth nor the Sun. Much more recently, beginning in 1892, dozens of far smaller Jovian moons have been detected and have received the names of lovers (or other sexual partners) or daughters of the Roman god Jupiter or his Greek equivalent Zeus. The Galilean moons are by far the largest and most massive objects to orbit Jupiter, with the remaining 78 known moons and the rings together composing just 0.003% of the total orbiting mass. Of Jupiter's moons, eight are regular satellites with prograde and nearly circular orbits that are not greatly inclined wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JunoCam
JunoCam (or JCM) is the visible-light camera/telescope onboard NASA's ''Juno'' spacecraft currently orbiting Jupiter. The camera is operated by the JunoCam Digital Electronics Assembly (JDEA). Both the camera and JDEA were built by Malin Space Science Systems. JunoCam takes a swath of imaging as the spacecraft rotates; the camera is fixed to the spacecraft, so as it rotates, it gets one sweep of observation. It has a field of view of 58 degrees with four filters (3 for visible light). Planned goals and outcome Originally, due to telecommunications constraints, ''Juno'' was expected to only be able to return about 40 megabytes of camera data during each 11-day orbital period (the orbital period was later modified). The downlink average data rate of around 325 bits per second will limit the number of images that are captured and transmitted during each orbit to somewhere between 10 and 100 depending on the compression level used. This is comparable to the previous ''Galileo'' m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Juno (spacecraft)
''Juno'' is a NASA space probe orbiting the planet Jupiter. It was built by Lockheed Martin and is operated by NASA Jet Propulsion Laboratory. The spacecraft was launched from Cape Canaveral Air Force Station on August 5, 2011 UTC, as part of the New Frontiers program. ''Juno'' entered a polar orbit of Jupiter on July 5, 2016, UTC, to begin a scientific investigation of the planet. After completing its mission, ''Juno'' will be intentionally deorbited into Jupiter's atmosphere. ''Juno'' mission is to measure Jupiter's composition, gravitational field, magnetic field, and polar magnetosphere. It will also search for clues about how the planet formed, including whether it has a rocky core, the amount of water present within the deep atmosphere, mass distribution, and its deep winds, which can reach speeds up to . ''Juno'' is the second spacecraft to orbit Jupiter, after the nuclear powered ''Galileo'' orbiter, which orbited from 1995 to 2003. Unlike all earlier spac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.svg "Click for more on -> Provisional Designation")
