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عدد المساهمات : 36 نقاط : 4830 السٌّمعَة : 13 تاريخ التسجيل : 30/12/2011 العمر : 64
| موضوع: What do you know about Solar Eclipse ? الأحد 13 مايو 2012, 4:38 pm | |
| As seen from the Earth [ Earth (or the Earth) is the third planet from the Sun and the densest and fifth-largest of the eight planets in the Solar System.], a solar eclipse occurs when the Moon passes between the Sun and the Earth, and the Moon [The Moon is Earth's only natural satellite and the fifth largest satellite in the Solar System.]fully or partially covers the Sun as viewed from a location on Earth. This can only happen during a new moon, when the Sun and Moon are in conjunction as seen from Earth. At least two, and up to five, solar eclipses occur each year.
The last total solar eclipse was the solar eclipse of July 11, 2010; the next will be the solar eclipse of November 13, 2012.
A total solar eclipse is a natural phenomenon. Nevertheless, in ancient times, and in some cultures today, solar eclipses have been attributed to supernatural causes or regarded as bad omens [ An omen is a phenomenon that is believed to foretell the future]. A total solar eclipse can be frightening to people who are unaware of their astronomical explanation, as the Sun seems to disappear during the day and the sky darkens in a matter of minutes.
Types of Solar eclipse There are four types of solar eclipses:
A total eclipse ,occurs when the dark shadow of the Moon completely obscures the bright disk of the Sun,allowing the much fainter solar corona to be visible. [ A corona is a type of plasma "atmosphere" of the Sun , extending millions of kilometers into space .The Greek root of the word corona means crown.]
An annular eclipse occurs when the Sun and Moon are exactly in line, but the apparent size of the Moon is smaller than that of the Sun. Hence the Sun appears as a very bright ring, or annulus, surrounding the outline of the Moon. A hybrid eclipse (also called annular/total eclipse) shifts between a total and annular eclipse. At some points on the surface of the Earth it appears as a total eclipse, whereas at others it appears as annular. Hybrid eclipses are comparatively rare. A partial eclipse occurs when the Sun and Moon are not exactly in line and the Moon only partially obscures the Sun.
Viewing the Sun during partial and annular eclipses requires special eye protection, or indirect viewing methods, to block the harmful part of the Sun's radiation to protect the eyes from being damaged. Sunglasses do not make viewing the sun safe. Only properly designed and certified solar filters should be used for direct viewing of the Sun's disk.
The safest way to view the Sun's disk is by indirect projection. This can be done by projecting an image of the disk onto a white piece of paper or card using a pair of binoculars (with one of the lenses covered), a telescope, or another piece of cardboard with a small hole in it (about 1 mm diameter), often called a pinhole camera.
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