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Siarnaq
Siarnaq, also designated Saturn XXIX, is the second-largest irregular moon of Saturn. It was discovered on 23 September 2000 by a team of astronomers led by Brett J. Gladman. It was named after the Inuit goddess of the sea, Siarnaq, who is more commonly known as Sedna. Siarnaq is the largest member of Saturn's Inuit group of prograde irregular moons, which orbit far from Saturn in the same direction as the planet's rotation. The moons of the Inuit group are believed to have originated as fragments from the collisional breakup of a larger progenitor moon after it was gravitationally captured into orbit around Saturn several billion years ago. Several other small Inuit group moons share similar orbits to Siarnaq, indicating that the moon had experienced another collision after forming from its progenitor. Discovery Siarnaq was discovered on 23 September 2000, by an international team of astronomers consisting of Brett J. Gladman, John J. Kavelaars, Jean-Marc Petit, Hans Sc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inuit Group
The Inuit group is a dynamical grouping of the prograde irregular satellites of Saturn which follow similar orbits. Their semi-major axes range between 11 and 18 Gm, their inclinations between 40° and 50°, and their eccentricities between 0.15 and 0.48. They take about 2 years to orbit Saturn. The International Astronomical Union (IAU) uses names taken from Inuit mythology for these moons. The group appeared quite homogeneous in early observations, the satellites displaying ''light-red'' colour ( colour indices B−V = 0.79 and V−R = 0.51, similar to that of the Gallic group)Grav, Tommy; Holman, Matthew J.; Gladman, Brett J.; Aksnes, Kaare ''Photometric survey of the irregular satellites'', Icarus, 166,(2003), pp. 33–45Preprint/ref> and similar infrared spectra.Tommy Grav and Matthew J. Holman ''Near-Infrared Photometry of the Irregular Satellites of Jupiter and Saturn'',The Astrophysical Journal, 605, (2004), pp. L141–L144Preprint/ref> Recent observations, however, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Irregular Moon
In astronomy, an irregular moon, irregular satellite or irregular natural satellite is a natural satellite following a distant, inclined, and often eccentric and retrograde orbit. They have been captured by their parent planet, unlike regular satellites, which formed in orbit around them. Irregular moons have a stable orbit, unlike temporary satellites which often have similarly irregular orbits but will eventually depart. The term does not refer to shape as Triton is a round moon, but is considered irregular due to its orbit. As of December 2022, 149 irregular moons are known, orbiting all four of the outer planets (Jupiter, Saturn, Uranus and Neptune). The largest of each planet are Himalia of Jupiter, Phoebe of Saturn, Sycorax of Uranus, and Triton of Neptune. It is currently thought that the irregular satellites were captured from heliocentric orbits near their current locations, shortly after the formation of their parent planet. An alternative theory, that they or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Irregular Satellite
In astronomy, an irregular moon, irregular satellite or irregular natural satellite is a natural satellite following a distant, inclined, and often eccentric and retrograde orbit. They have been captured by their parent planet, unlike regular satellites, which formed in orbit around them. Irregular moons have a stable orbit, unlike temporary satellites which often have similarly irregular orbits but will eventually depart. The term does not refer to shape as Triton is a round moon, but is considered irregular due to its orbit. As of December 2022, 149 irregular moons are known, orbiting all four of the outer planets (Jupiter, Saturn, Uranus and Neptune). The largest of each planet are Himalia of Jupiter, Phoebe of Saturn, Sycorax of Uranus, and Triton of Neptune. It is currently thought that the irregular satellites were captured from heliocentric orbits near their current locations, shortly after the formation of their parent planet. An alternative theory, that they originat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cassini (spacecraft)
Cassini may refer to: People * Cassini (surname) * Oleg Cassini (1913-2006), American fashion designer :Cassini family: * Giovanni Domenico Cassini (1625–1712), Italian mathematician, astronomer, engineer, and astrologer * Jacques Cassini (1677–1756), French astronomer, son of Giovanni Domenico Cassini * César-François Cassini de Thury (1714–1784), French astronomer and cartographer, son of Jacques Cassini * Jean-Dominique, comte de Cassini (1748–1845), French astronomer, son of César-François Cassini de Thury * Alexandre Henri Gabriel de Cassini (1781–1832), French botanist and naturalist, son of Jean-Dominique de Cassini Planetary science * Cassini's laws on the motion of the Moon * Cassini Division, a gap in the rings of Saturn * '' Cassini–Huygens'', the space mission to examine Saturn and its moons, of which the ''Cassini'' orbiter was a part * Cassini (Martian crater) * Cassini (lunar crater) * 24101 Cassini, an asteroid * 24102 Jacquescassini, another as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saturn
Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; however, with its larger volume, Saturn is over 95 times more massive. Saturn's interior is most likely composed of a core of iron–nickel alloy, iron–nickel and rock (silicon and oxygen compounds). Its core is surrounded by a deep layer of metallic hydrogen, an intermediate layer of liquid hydrogen and liquid helium, and finally, a gaseous outer layer. Saturn has a pale yellow hue due to ammonia crystals in its upper atmosphere. An electrical current within the metallic hydrogen layer is thought to give rise to Saturn's planetary magnetic field, which is weaker than Earth's, but which has a magnetic moment 580 times that of Earth due to Saturn's larger size. Saturn's magnetic field strength is around one-twentieth of Jupiter's. The out ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hill Sphere
The Hill sphere of an astronomical body is the region in which it dominates the attraction of satellites. To be retained by a planet, a moon must have an orbit that lies within the planet's Hill sphere. That moon would, in turn, have a Hill sphere of its own. Any object within that distance would tend to become a satellite of the moon, rather than of the planet itself. One simple view of the extent of the Solar System is the Hill sphere of the Sun with respect to local stars and the galactic nucleus. In more precise terms, the Hill sphere approximates the gravitational sphere of influence of a smaller body in the face of perturbations from a more massive body. It was defined by the American astronomer George William Hill, based on the work of the French astronomer Édouard Roche. In the example to the right, the Earth's Hill sphere extends between the Lagrange points and , which lie along the line of centers of the two bodies. The region of influence of the smaller body i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charged Coupled Device
A charge-coupled device (CCD) is an integrated circuit containing an array of linked, or coupled, capacitors. Under the control of an external circuit, each capacitor can transfer its electric charge to a neighboring capacitor. CCD sensors are a major technology used in digital imaging. In a CCD image sensor, pixels are represented by p-doped metal–oxide–semiconductor (MOS) capacitors. These MOS capacitors, the basic building blocks of a CCD, are biased above the threshold for inversion when image acquisition begins, allowing the conversion of incoming photons into electron charges at the semiconductor-oxide interface; the CCD is then used to read out these charges. Although CCDs are not the only technology to allow for light detection, CCD image sensors are widely used in professional, medical, and scientific applications where high-quality image data are required. In applications with less exacting quality demands, such as consumer and professional digital cameras, ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ground-based Telescope
The following are lists of devices categorized as types of telescopes or devices associated with telescopes. They are broken into major classifications with many variations due to professional, amateur, and commercial sub-types. Telescopes can be classified by optical design or mechanical design/construction. Telescopes can also be classified by where they are placed, such as space telescopes. One major determining factor is type of light, or particle being observed including devices referred to as "telescopes" that do not form an image or use optics. Some telescopes are classified by the task they perform; for example Solar telescopes are all designs that look at the Sun, Dobsonian telescopes are designed to be low cost and portable, Aerial telescopes overcame the optical shortcomings of 17th-century objective lenses, etc. List of optical telescope types Optical telescopes can be classified by three primary optical designs (refractor, reflector, or catadioptric), by sub-designs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gravitational Capture
Gravitational capture occurs when one object enters a stable orbit around another (typically referring to natural orbits rather than orbit insertion of a spacecraft with an orbital maneuvers). Asteroid capture turns a star-orbiting asteroid into an irregular moon if captured permanently, or a temporary satellite. Capture events explain how satellites can end up with retrograde orbits or rotation. Planetary capture of a rogue planet by a star or other planet is also theoretically possible, but , none has yet been directly observed. Because the angle of encounter is somewhat random, such an event would likely leave the captured planet in an orbit outside the orbital plane of other planets in the solar system, possibly in a retrograde orbit. Planetary capture has been proposed one mechanism that could explain the unusual orbit of the hypothesized Planet Nine in the Earth's solar system. (Planetary migration is a competing explanation.) Planetary capture (possibly planet swapping wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Impact Event
An impact event is a collision between astronomical objects causing measurable effects. Impact events have physical consequences and have been found to regularly occur in planetary systems, though the most frequent involve asteroids, comets or meteoroids and have minimal effect. When large objects impact terrestrial planets such as the Earth, there can be significant physical and biospheric consequences, though atmospheres mitigate many surface impacts through atmospheric entry. Impact craters and structures are dominant landforms on many of the Solar System's solid objects and present the strongest empirical evidence for their frequency and scale. Impact events appear to have played a significant role in the evolution of the Solar System since its formation. Major impact events have significantly shaped Earth's history, and have been implicated in the formation of the Earth–Moon system. Impact events also appear to have played a significant role in the evolutionary hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retrograde And Prograde Motion
Retrograde motion in astronomy is, in general, orbital or rotational motion of an object in the direction opposite the rotation of its primary, that is, the central object (right figure). It may also describe other motions such as precession or nutation of an object's rotational axis. Prograde or direct motion is more normal motion in the same direction as the primary rotates. However, "retrograde" and "prograde" can also refer to an object other than the primary if so described. The direction of rotation is determined by an inertial frame of reference, such as distant fixed stars. In the Solar System, the orbits around the Sun of all planets and most other objects, except many comets, are prograde. They orbit around the Sun in the same direction as the sun rotates about its axis, which is counterclockwise when observed from above the Sun's north pole. Except for Venus and Uranus, planetary rotations around their axes are also prograde. Most natural satellites have prograd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
