|
L-shell
The L-shell, L-value, or McIlwain L-parameter (after Carl E. McIlwain) is a parameter describing a particular set of planetary magnetic field lines. Colloquially, L-value often describes the set of magnetic field lines which cross the Earth's magnetic equator at a number of Earth-radii equal to the L-value. For example, "L=2" describes the set of the Earth's magnetic field lines which cross the Earth's magnetic equator two earth radii from the center of the Earth. L-shell parameters can also describe the magnetic fields of other planets. In such cases, the parameter is renormalized for that planet's radius and magnetic field model.Galileo - Glossary of Selected Terms'' NASA Jet Propulsion Laboratory, (2003). Although L-value is formally defined in terms of the Earth's true instantaneous magnetic field (or a high-order model like IGRF), it is often used to give a general picture of magnetic phenomena near the Earth, in which case it can be approximated using the dipole m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dipole Model Of The Earth's Magnetic Field
The dipole model of the Earth's magnetic field is a first order approximation of the rather complex true Earth's magnetic field. Due to effects of the interplanetary magnetic field (IMF), and the solar wind, the dipole model is particularly inaccurate at high L-shells (e.g., above L=3), but may be a good approximation for lower L-shells. For more precise work, or for any work at higher L-shells, a more accurate model that incorporates solar effects, such as the Tsyganenko magnetic field model, is recommended. Formulation The following equations describe the dipole magnetic field. First, define B_0 as the mean value of the magnetic field at the magnetic equator on the Earth's surface. Typically B_0=3.12\times10^\ \textrm. Then, the radial and latitudinal fields can be described as :B_r = -2B_0\left(\frac\right)^3\cos\theta :B_\theta = -B_0\left(\frac\right)^3\sin\theta :, B, = B_0\left(\frac\right)^3 \sqrt where R_E is the mean radius of the Earth (approximately 6370&n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aurora (astronomy)
An aurora (plural: auroras or aurorae), also commonly known as the polar lights, is a natural light display in Earth's sky, predominantly seen in high-latitude regions (around the Arctic and Antarctic). Auroras display dynamic patterns of brilliant lights that appear as curtains, rays, spirals, or dynamic flickers covering the entire sky. Auroras are the result of disturbances in the magnetosphere caused by the solar wind. Major disturbances result from enhancements in the speed of the solar wind from coronal holes and coronal mass ejections. These disturbances alter the trajectories of charged particles in the magnetospheric plasma. These particles, mainly electrons and protons, precipitate into the upper atmosphere (thermosphere/ exosphere). The resulting ionization and excitation of atmospheric constituents emit light of varying colour and complexity. The form of the aurora, occurring within bands around both polar regions, is also dependent on the amount of accelerati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geomagnetic Latitude
Geomagnetic latitude, or magnetic latitude (MLAT), is a parameter analogous to geographic latitude, except that, instead of being defined relative to the geographic poles, it is defined by the axis of the geomagnetic dipole, which can be accurately extracted from the International Geomagnetic Reference Field (IGRF). See also * Earth's magnetic field * Geomagnetic equator * Ionosphere * L-shell * Magnetosphere * World Magnetic Model (WMM) References External links Space Weather: Maps of Geomagnetic Latitude(Northwest Research Associates) Tips on Viewing the Aurora( SWPC) Magnetic Field Calculator(NCEI The National Centers for Environmental Information (NCEI), an agency of the United States government The federal government of the United States (U.S. federal government or U.S. government) is the national government of the United St ...) Ionospheric Electrodynamics Using Magnetic Apex Coordinates( Journal of Geomagnetism and Geoelectricity) Geomagnetism Geo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Mirror Point
In astrophysics, a magnetic mirror point is a point where the motion of a charged particle trapped in a magnetic field (such as the (approximately) dipole field of the Earth) reverses its direction. More precisely, it is the point where the projection of the particle's velocity vector in the direction of the field vector is equal to zero. See also * Magnetic mirror A magnetic mirror, known as a magnetic trap (магнитный захват) in Russia and briefly as a pyrotron in the US, is a type of magnetic confinement device used in fusion power to trap high temperature plasma using magnetic fields. T ... * L-shell * Dipole model of the Earth's magnetic field * List of artificial radiation belts References Astrophysics {{Astrophysics-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
L Shell Global Dipole
L, or l, is the twelfth letter in the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''el'' (pronounced ), plural ''els''. History Lamedh may have come from a pictogram of an ox goad or cattle prod. Some have suggested a shepherd's staff. Use in writing systems Phonetic and phonemic transcription In phonetic and phonemic transcription, the International Phonetic Alphabet uses to represent the lateral alveolar approximant. English In English orthography, usually represents the phoneme , which can have several sound values, depending on the speaker's accent, and whether it occurs before or after a vowel. The alveolar lateral approximant (the sound represented in IPA by lowercase ) occurs before a vowel, as in ''lip'' or ''blend'', while the velarized alveolar lateral approximant (IPA ) occurs in ''bell'' and ''milk''. This velarization does not occur in many European lang ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pitch Angle (particle Motion)
The pitch angle of a charged particle is the angle between the particle's velocity vector and the local magnetic field. This is a common measurement and topic when studying the magnetosphere, magnetic mirrors, biconic cusps and polywells. See Aurora and Ring current Usage: particle motion It is customary to discuss the direction a particle is heading by its pitch angle. A pitch angle of 0 degrees is a particle whose parallel motion is perfectly along the local magnetic field. In the northern hemisphere this particle would be heading down toward the Earth (and the opposite in the southern hemisphere). A pitch angle of 90 degrees is a particle that is locally mirroring (see: Magnetosphere particle motion). Special case: equatorial pitch angle The equatorial pitch angle of a particle is the pitch angle of the particle at the Earth's geomagnetic equator. This angle defines the loss cone of a particle. The loss cone is the set of angles where the particle will strike the atmosph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Icarus (journal)
''ICARUS'' is a scientific journal dedicated to the field of planetary science. It is officially endorsed by the American Astronomical Society's Division for Planetary Sciences (DPS). The journal contains articles discussing the results of new research on astronomy, geology, meteorology, physics, chemistry, biology, and other scientific aspects of the Solar System or extrasolar systems. The journal was founded in 1962, and became affiliated with the DPS in 1974. Its original owner and publisher was Academic Press, which was purchased by Elsevier in 2000. The journal is named for the mythical Icarus, and the frontispiece of every issue contains an extended quotation from Sir Arthur Eddington equating Icarus' adventurousness with the scientific investigator who "strains his theories to the breaking-point till the weak joints gape." Abstracting and indexing This journal is indexed by the following services: * Science Citation Index * Current Contents /Physical, Chemical & E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Imke De Pater
Imke de Pater is a Dutch astronomer working at the University of California, Berkeley. She is known for her research on the large planets and led the team using the Keck Telescope to image the 1994 impact of the comet Comet Shoemaker–Levy 9 with Jupiter. Education and career De Pater was introduced to astronomy in high school when a family friend gave her an astronomy textbook and introduced her to someone in Utrecht so she could learn about the field. She earned her Ph.D. from Leiden University (1980) while working on radio emissions from Jupiter. de Pater is a professor of astronomy, earth and planetary science from the University of California, Berkeley, and served as the chair of the Astronomy Department. In 2015 year, De Pater was named a fellow of the American Geophysical Union who cited her for: Research De Pater's research centers on observations of the large planets and their rings and satellites (Jupiter, Neptune, Titan, and Uranus) using adaptive optics and rad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetosphere Of Jupiter
The magnetosphere of Jupiter is the cavity created in the solar wind by the planet's magnetic field. Extending up to seven million kilometers in the Sun's direction and almost to the orbit of Saturn in the opposite direction, Jupiter's magnetosphere is the largest and most powerful of any planetary magnetosphere in the Solar System, and by volume the largest known continuous structure in the Solar System after the heliosphere. Wider and flatter than the Earth's magnetosphere, Jupiter's is stronger by an order of magnitude, while its magnetic moment is roughly 18,000 times larger. The existence of Jupiter's magnetic field was first inferred from observations of radio emissions at the end of the 1950s and was directly observed by the Pioneer 10 spacecraft in 1973. Jupiter's internal magnetic field is generated by electrical currents in the planet's outer core, which is composed of liquid metallic hydrogen. Volcanic eruptions on Jupiter's moon Io eject large amounts of sulfur diox ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasmapause
The plasmasphere, or inner magnetosphere, is a region of the Earth's magnetosphere consisting of low-energy (cool) plasma. It is located above the ionosphere. The outer boundary of the plasmasphere is known as the plasmapause, which is defined by an order of magnitude drop in plasma density. In 1963 American scientist Don Carpenter and Soviet astronomer proved the plasmasphere and plasmapause's existence from the analysis of very low frequency (VLF) whistler wave data. Traditionally, the plasmasphere has been regarded as a well behaved cold plasma with particle motion dominated entirely by the geomagnetic field and, hence, co-rotating with the Earth. History The discovery of the plasmasphere grew out of the scientific study of whistlers, natural phenomena caused by very low frequency (VLF) radio waves. Whistlers were first heard by radio operators in the 1890s. British scientist Llewelyn Robert Owen Storey had shown lightning generated whistlers in his 1953 PhD dissertation. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geomagnetic Storm
A geomagnetic storm, also known as a magnetic storm, is a temporary disturbance of the Earth's magnetosphere caused by a solar wind shock wave and/or cloud of magnetic field that interacts with the Earth's magnetic field. The disturbance that drives the magnetic storm may be a solar coronal mass ejection (CME) or (much less severely) a co-rotating interaction region (CIR), a high-speed stream of solar wind originating from a coronal hole. The frequency of geomagnetic storms increases and decreases with the sunspot cycle. During solar maximum, geomagnetic storms occur more often, with the majority driven by CMEs. The increase in the solar wind pressure initially compresses the magnetosphere. The solar wind's magnetic field interacts with the Earth's magnetic field and transfers an increased energy into the magnetosphere. Both interactions cause an increase in plasma movement through the magnetosphere (driven by increased electric fields inside the magnetosphere) and an increase i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> Imke De Pater")
