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It is the international standard empirical model for the terrestrial ionosphere since 1999. For a specified geographic location, time, and date, IRI provides average monthly values for electron density, electron temperature and ion temperature, and the molecular composition of the ions in the range of altitudes from 50 km to 2000 km. [ 1 ] The ...
An ionospheric model is a mathematical description of the ionosphere as a function of location, altitude, day of year, phase of the sunspot cycle and geomagnetic activity. Geophysically, the state of the ionospheric plasma may be described by four parameters: electron density, electron and ion temperature and, since several species of ions are ...
The IPP or Ionospheric Pierce Point is the altitude in the ionosphere where electron density is greatest. [ 1 ] These points can change based on factors like time of day, solar activity, and geographical location, which all influence ionospheric conditions.
EUV was a 1-dimension limb imager designed to observe height and density of the daytime ionosphere by detecting the glow of oxygen ions and other species at wavelengths between 55 and 85 nm. FUV was a 2-dimension imager that observes the limb and below at 135 and 155 nm, where bright emissions of atomic oxygen and molecular nitrogen are found.
A similar cosmological model was independently proposed in the Hindu astronomical treatise Tantrasamgraha (c. 1500 CE) by Nilakantha Somayaji of the Kerala school of astronomy and mathematics. [ 4 ] It is conceptually a geocentric model , or more precisely geoheliocentric: the Earth is at the centre of the universe, the Sun and Moon and the ...
A successful large-scale simulation of the evolution of galaxies, with results consistent with what is actually seen by astronomers in the night sky, provides evidence that the theoretical underpinnings of the models employed, i.e., the supercomputer implementations ΛCDM, are sound bases for understanding galactic dynamics and the history of the universe, and opens avenues to further research.
Heliocentrism [a] (also known as the heliocentric model) is a superseded astronomical model in which the Earth and planets orbit around the Sun at the center of the universe. Historically, heliocentrism was opposed to geocentrism , which placed the Earth at the center.
While the Big Bang model in cosmology is sometimes said to derive from the Copernican principle in conjunction with redshift observations, the Big Bang model can still be assumed to be valid in absence of the Copernican principle, because the cosmic microwave background, primordial gas clouds, and the structure, evolution, and distribution of ...