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Irregular Satellites
In astronomy, an irregular moon, irregular satellite, or irregular natural satellite is a natural satellite following an orbit that is irregular in some of the following ways: Distant; orbital inclination, inclined; orbital eccentricity, highly elliptical; Retrograde and prograde motion, retrograde. They have often been Asteroid capture, captured by their parent planet, unlike regular satellites 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; Triton (moon), Triton, for example, is a planetary-mass moon, round moon but is considered irregular due to its orbit and origins. , 356 irregular moons are known, orbiting all four of the outer planets (Jupiter, Saturn, Uranus, and Neptune). The largest of each planet are Himalia (moon), Himalia of Jupiter, Phoebe (moon), Phoebe of Saturn, Sycorax (moon), Sycorax of Uranus, and Triton (moon), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phoebe (moon)
Phoebe ( ) is the most massive irregular satellite, irregular Moons of Saturn, satellite of Saturn with a mean diameter of . It was discovered by William Henry Pickering on 18 March 1899 from photographic plates that had been taken by DeLisle Stewart starting on 16 August 1898 at the Boyden Observatory, Boyden Station of the Carmen Alto Observatory near Arequipa, Peru. It was the first natural satellite to be discovered photographically. Phoebe was the first target encountered upon the arrival of the ''Cassini–Huygens, Cassini'' spacecraft in the Saturn system in 2004, and is thus unusually well-studied for an irregular moon of its size. ''Cassinis trajectory to Saturn and time of arrival were chosen to permit this flyby. After the encounter and its insertion into orbit, ''Cassini'' did not go much beyond the orbit of Iapetus (moon), Iapetus. Phoebe is roughly spherical and has a differentiated interior. It was spherical and hot early in its history and was battered out of rou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sycorax (moon)
Sycorax is the largest irregular satellite of Uranus. It was discovered in September, 1997 on the Hale Telescope in California. Sycorax's orbit is retrograde, irregular, and much more distant than that of Oberon, the furthest of Uranus's regular moons. With a diameter of over , it is the largest irregular moon of Uranus. It has been hypothesized that Sycorax is a captured object, as opposed to one formed with Uranus. Discovery Sycorax was discovered on 6 September 1997 by Brett J. Gladman, Philip D. Nicholson, Joseph A. Burns, and John J. Kavelaars using the 200-inch Hale Telescope, together with Caliban. At the time, it was given the temporary designation S/1997 U 2. Officially confirmed as Uranus XVII, it was named after Sycorax, Caliban's mother in William Shakespeare's play ''The Tempest''. This follows the trend that all Uranian moons are named after Shakespearean characters or those from Alexander Pope's '' The Rape of the Lock''. Orbit Sycorax f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Irregular Moon Orbits A Vs
Irregular, irregulars or irregularity may refer to any of the following: Astronomy * Irregular galaxy * Irregular moon * Irregular variable, a kind of star Language * Irregular inflection, the formation of derived forms such as plurals in unpredictable ways ** Irregular verb Law * Against regulations * In canon law, an irregularity is an impediment for the Catholic priesthood or for exercising orders already received Mathematics * Irregularity of a surface * Irregularity of distributions * Irregularity index Medicine * Irregular bone * Arrhythmia, also known as an irregular heartbeat * Constipation, also called "irregularity" Other * ''The Irregulars'', a 2021 Netflix series * Accounting irregularity * Irregular military * Irregular chess opening See also * Anomaly (other) * Baker Street Irregulars The Baker Street Irregulars are fictional characters who appear in three Sherlock Holmes stories, specifically two novels and one short story, by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iapetus (moon)
Iapetus () is the outermost of Moons of Saturn, Saturn's large moons. With an estimated diameter of , it is the third-largest moon of Saturn and the List of natural satellites, eleventh-largest in the Solar System. Named after the Titans, Titan Iapetus, the moon was discovered in 1671 by Giovanni Domenico Cassini. A relatively low-density body made up mostly of ice, Iapetus is home to several distinctive and unusual features, such as a striking difference in coloration between its leading hemisphere, which is dark, and its trailing hemisphere, which is bright, as well as a massive Equatorial ridge on Iapetus, equatorial ridge running three-quarters of the way around the moon. History Discovery Iapetus was discovered by Giovanni Domenico Cassini, an Italian-born French astronomer, in October 1671. This is the first moon that Cassini discovered; the second moon of Saturn to be discovered after Christiaan Huygens spotted Titan (moon), Titan 16 years prior in 1655; and the sixth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moon
The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar day) that is synchronized to its orbital period (Lunar month#Synodic month, lunar month) of 29.5 Earth days. This is the product of Earth's gravitation having tidal forces, tidally pulled on the Moon until one part of it stopped rotating away from the near side of the Moon, near side, making always the same lunar surface face Earth. Conversley, the gravitational pull of the Moon, on Earth, is the main driver of Earth's tides. In geophysical definition of planet, geophysical terms, the Moon is a planetary-mass object or satellite planet. Its mass is 1.2% that of the Earth, and its diameter is , roughly one-quarter of Earth's (about as wide as the contiguous United States). Within the Solar System, it is the List of Solar System objects by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apoapsis
An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides pertaining to orbits around different bodies have distinct names to differentiate themselves from other apsides. Apsides pertaining to geocentric orbits, orbits around the Earth, are at the farthest point called the ''apogee'', and at the nearest point the ''perigee'', like with orbits of satellites and the Moon around Earth. Apsides pertaining to orbits around the Sun are named ''aphelion'' for the farthest and ''perihelion'' for the nearest point in a heliocentric orbit. Earth's two apsides are the farthest point, ''aphelion'', and the nearest point, ''perihelion'', of its orbit around the host Sun. The terms ''aphelion'' and ''perihelion'' apply in the same way to the orbits of Jupiter and the other planets, the comets, and the asteroids of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hill Sphere
The Hill sphere is a common model for the calculation of a Sphere of influence (astrodynamics), gravitational sphere of influence. It is the most commonly used model to calculate the spatial extent of gravitational influence of an astronomical body (''m'') in which it dominates over the gravitational influence of other bodies, particularly a Primary (astronomy), primary (''M''). It is sometimes confused with other models of gravitational influence, such as the Laplace sphere or being named the Roche sphere, the latter causing confusion with the Roche limit. It was defined by the United States, American astronomer George William Hill, based on the work of the France, French astronomer Édouard Roche. To be retained by a more gravitationally attracting astrophysical object—a planet by a more massive star, a natural satellite, moon by a more massive planet—the less massive body must have an orbit that lies within the gravitational potential represented by the more massive body ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semi-major Axis
In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the longest semidiameter or one half of the major axis, and thus runs from the centre, through a focus, and to the perimeter. The semi-minor axis (minor semiaxis) of an ellipse or hyperbola is a line segment that is at right angles with the semi-major axis and has one end at the center of the conic section. For the special case of a circle, the lengths of the semi-axes are both equal to the radius of the circle. The length of the semi-major axis of an ellipse is related to the semi-minor axis's length through the eccentricity and the semi-latus rectum \ell, as follows: The semi-major axis of a hyperbola is, depending on the convention, plus or minus one half of the distance between the two branches. Thus it is the distance from the ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jet Propulsion Laboratory
The Jet Propulsion Laboratory (JPL) is a Federally funded research and development centers, federally funded research and development center (FFRDC) in La Cañada Flintridge, California, Crescenta Valley, United States. Founded in 1936 by California Institute of Technology (Caltech) researchers, the laboratory is now owned and sponsored by NASA and administered and managed by Caltech. The primary function of the laboratory is the construction and operation of planetary robotic spacecraft, though it also conducts Earth-orbit and astronomy missions. It is also responsible for operating the NASA Deep Space Network (DSN). Among the major active projects at the laboratory, some are the Mars 2020 mission, which includes the ''Perseverance (rover), Perseverance'' rover; the Mars Science Laboratory mission, including the ''Curiosity (rover), Curiosity'' rover; the ''Mars Reconnaissance Orbiter''; the ''Juno (spacecraft), Juno'' spacecraft orbiting Jupiter; the ''Soil Moisture Active P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Plane (astronomy)
The orbital plane of a revolving body is the geometric plane in which its orbit lies. Three non-collinear points in space suffice to determine an orbital plane. A common example would be the positions of the centers of a massive body (host) and of an orbiting celestial body at two different times/points of its orbit. The orbital plane is defined in relation to a reference plane by two parameters: inclination (''i'') and longitude of the ascending node (Ω). By definition, the reference plane for the Solar System is usually considered to be Earth's orbital plane, which defines the ecliptic, the circular path on the celestial sphere that the Sun appears to follow over the course of a year. In other cases, for instance a moon or artificial satellite orbiting another planet, it is convenient to define the inclination of the object's orbit as the angle between its orbital plane and the planet's equatorial plane. The coordinate system defined that uses the orbital plane a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precession
Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In other words, if the axis of rotation of a body is itself rotating about a second axis, that body is said to be precessing about the second axis. A motion in which the second Euler angle changes is called '' nutation''. In physics, there are two types of precession: torque-free and torque-induced. In astronomy, ''precession'' refers to any of several slow changes in an astronomical body's rotational or orbital parameters. An important example is the steady change in the orientation of the axis of rotation of the Earth, known as the precession of the equinoxes. Torque-free or torque neglected Torque-free precession implies that no external moment (torque) is applied to the body. In torque-free precession, the angular momentum is a constant, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Degree (angle)
A degree (in full, a degree of arc, arc degree, or arcdegree), usually denoted by ° (the degree symbol), is a measurement of a plane (mathematics), plane angle in which one Turn (geometry), full rotation is 360 degrees. It is not an SI unit—the SI unit of angular measure is the radian—but it is mentioned in the SI Brochure, SI brochure as an Non-SI units mentioned in the SI, accepted unit. Because a full rotation equals 2 radians, one degree is equivalent to radians. History The original motivation for choosing the degree as a unit of rotations and angles is unknown. One theory states that it is related to the fact that 360 is approximately the number of days in a year. Ancient astronomers noticed that the sun, which follows through the ecliptic path over the course of the year, seems to advance in its path by approximately one degree each day. Some ancient calendars, such as the Iranian calendar, Persian calendar and the Babylonian calendar, used 360 days for a year. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
