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1999 solar eclipse seen from Mir space station
An eclipse occurs when an astronomical body such as a planet, or satellite is between a source of light (e.g. the Sun) and another body. For instance, Jupiter eclipses its moons when it gets between them and the Sun.
The most dramatic eclipses from Earth are:
Total eclipses occur where the light source is totally blocked off by the eclipsing body. For total solar eclipses, the viewer is in the umbraA different sense of the word "umbra", used in mathematics, is explained in the article titled umbral calculus. The umbra ( Latin for shadow) is the darkest part of a shadow. From within the umbra, the source of light is completely blocked by the object c part of the Moon's shadow.
Partial eclipses occur at places where only part of the luminary is covered (solar eclipses), or when only part of a body is eclipsed by the shadow (lunar eclipses). For solar eclipses, the viewer is in the penumbraThe penumbra ( Latin for mid- shadow) is the portion of a shadow that results from the source of illumination being only partially blocked. Penumbras only occur when the source of light is not a point-source. As the sun is a visible disc, solar shadows ha part of the Moon's shadow.
An annular eclipse is a total eclipse of luminary where a thin ring of light is visible around the intervening object. For solar eclipses, the viewer is in the antumbra part of the Moon's shadow. It is sheer coincidence that the Moon and Sun have nearly equal apparent sizes, making annular eclipses possible. Annular eclipses are ideal times for observing solar prominence s.
An eclipse involving the Sun, Earth and Moon can only occur when they are in a line. Because the plane of the orbitFor other meanings of the term "orbit", see orbit (disambiguation In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. History Orbits were first analyse of the Moon is tilted with respect to the plane of the orbitFor other meanings of the term "orbit", see orbit (disambiguation In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. History Orbits were first analyse of the Earth (the eclipticThe ecliptic is the geometric plane that contains the orbit of the Earth. The orbits of most planets in the Solar System lie very close to it. Seen from the Earth, this is a bisecting great circle, superimposed upon the celestial sphere, which contains th), eclipses occur only when the three bodies are near the intersection (the nodeA node is one of two points where a body's orbit crosses the ecliptic, called the ascending node (when the body is moving northward) and descending node (when the body is moving southward). The lunar nodes are subject to lunar precession, this is the grad) of these planes. The Sun passes either node once a yearA year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. By extension, this can be applied to any planet: for example, "Martian year". Seasonal year A seasonal year is the time between successive recurrences, and eclipses occur in a period of about two draconic months around these times. There can be from two to seven eclipses in a calendar year. They repeat according to eclipse cycles.
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