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| Solar eclipses | |
|---|---|
| Name | Solar eclipses |
| Type | Astronomical event |
| Discovered | Ancient observations |
| Discovered by | Various cultures |
Solar eclipses are astronomical events that occur when the Moon passes between the Sun and the Earth, casting a shadow that partially or wholly obscures the solar disk as seen from particular locations on Earth. These events have been observed and recorded by civilizations such as the Babylonian Empire, Ancient China, the Roman Empire, and the Maya civilization and studied by astronomers associated with institutions like the Royal Observatory, Greenwich, the Mount Wilson Observatory, and the Harvard College Observatory. Modern investigations involve agencies including NASA, the European Space Agency, and observatories such as Mauna Kea Observatories and Kitt Peak National Observatory.
Solar eclipses arise from the alignment of the Sun, Moon, and Earth along the lunar orbital plane called the ecliptic. Observers located in the Moon's shadow path witness phenomena historically recorded by figures like Thales of Miletus and chronicled in annals of the Han dynasty, the Sumerians, and the Tang dynasty. Major research programs at institutions such as MIT, Caltech, and Stanford University coordinate observations with facilities like the Very Large Array and the Atacama Large Millimeter Array to study solar corona structure and space weather effects.
Eclipse geometry produces several classifications: total, annular, partial, and hybrid events. A total eclipse occurs when the Moon completely covers the Sun as viewed from the umbral path, studied during expeditions led by explorers like Christopher Columbus and scientists such as Arthur Eddington and Isaac Newton who leveraged eclipses for tests of gravitational theory. Annular eclipses leave a bright ring and were recorded by observers during voyages like those of James Cook; partial eclipses are common and were cataloged by teams at the Royal Astronomical Society and the Bureau des Longitudes. Hybrid eclipses shift between total and annular along the path and have been analyzed using models developed at Princeton University and the Max Planck Institute for Solar System Research.
The mechanics involve lunar orbital elements—inclination, eccentricity, and node regression—and the interplay of apparent angular diameters of the Sun and the Moon. Calculations employ perturbation theories refined by mathematicians and astronomers at institutions such as Uppsala University, University of Cambridge, and Sorbonne University. Key parameters include the synodic month, anomalistic month, and nodal precession, topics advanced by figures like Johannes Kepler, Pierre-Simon Laplace, and Simon Newcomb. Numerical ephemerides produced by the Jet Propulsion Laboratory and the International Astronomical Union underpin precise path predictions.
Safe observation practices recommend indirect methods endorsed by organizations such as American Astronomical Society, Royal Society, and Health and Safety Executive (UK), including solar filters compliant with standards promulgated by ISO and equipment supplied by vendors linked to institutions like STScI and SpaceX outreach programs. Direct viewing without certified filters risks retinal damage documented in case reports from hospitals affiliated with Johns Hopkins Hospital and Mayo Clinic. Professional observations use coronagraphs at facilities like Big Bear Solar Observatory and spectrometers deployed by teams from University of Colorado Boulder and Leiden Observatory.
Eclipses influenced political and religious actions in societies such as the Inca Empire, Ottoman Empire, and Edo period Japan. Historic events include the eclipse cited during the Battle of Halys (the "Battle of the Eclipse") and eclipse records used to date reigns in the Neo-Assyrian Empire and synchronize chronicles from the Byzantine Empire and Umayyad Caliphate. Cultural responses appear in works like the Iliad and folklore compiled by scholars at the British Museum and the Metropolitan Museum of Art; celestial omens figure in correspondence of rulers such as Alexander the Great and Qin Shi Huang.
Eclipses provide unique opportunities to probe the solar corona, test theories in general relativity, and study ionospheric responses. Classic tests include the 1919 expedition led by Arthur Eddington which used stars near the eclipsed Sun to validate Albert Einstein's theory, and later measurements at observatories such as Yerkes Observatory and Palomar Observatory. Research programs at NASA Goddard Space Flight Center, European Southern Observatory, and National Center for Atmospheric Research deploy instrumentation to measure coronal mass ejections, magnetic topology, and solar wind acceleration. Eclipses also enable calibration of space-based instruments on missions like SOHO, Parker Solar Probe, and STEREO.
Predictive capability relies on cycles such as the Saros cycle and computational ephemerides generated by organizations including the US Naval Observatory and the International Earth Rotation and Reference Systems Service. Average global frequency yields about two to five eclipses involving the Moon and Sun per year, with totalities visible from narrow terrestrial paths documented in catalogs maintained by Royal Observatory Edinburgh and the Astronomical Society of the Pacific. Historical eclipse chronologies assembled by researchers at Cambridge University Press and Oxford University Press assist archaeologists and historians in cross-dating events in chronologies like those of the Vikings and the Aztec Empire.
Category:Astronomical events