The passage of the shadow of a celestial body over the surface of
another. The maximum number of solar and lunar visible
eclipses occurring annually is seven; the minimum number is two, both being solar.
→ Solar eclipses take place when the new Moon is close to an
→ orbital node and on the same longitude with the Sun. At that moment
either the → umbra, → antumbra, or the
→ penumbra touches the Earth’s surface. For an observer located in the
umbra the eclipse is total, while for one placed in the antumbra
it is annular. → Annular eclipses occur around lunar
→ apogee. An observer situated in the penumbra sees only a
→ partial eclipse. A total or annular eclipse can be seen from a band with a
width of 270 km at the most, around which, the
much larger partiality zone extends. The Moon’s shadow crosses the
Earth from west to east at about 3,200 km/h. During
→ total eclipses the Sun’s disk is entirely covered and the
→ solar corona can be seen. A
solar eclipse can last up to 3 h (between the first and the
→ fourth contacts). Totality has a theoretical maximum duration of 7m 31s, but
it is usually shorter.
A → lunar eclipse can be seen from any place on Earth where the
Moon is above the horizon; it occurs when the full Moon passes through the central
dark shadow of the Earth. The Earth’s
shadow is much wider than the Moon and this is why the lunar eclipses can
last up to four hours (between the first and the fourth
contact) (M.S.: SDE).
Etymology (EN): From O.Fr. éclipse, from L. eclipsis, from Gk. ekleipsis “a leaving
out, forsaking, an eclipse,” from ekleipein “to forsake a usual
place, fail to appear, be eclipsed,” from ek “out,” → ex-,
Etymology (PE): Gereft, past stem of gereftan
“to obscure, close up; to take, seize, catch; to undergo an eclipse,” from Mid.Pers.
griftan, Av./O.Pers. grab- “to take, seize,” cf.
Skt. grah-, grabh- “to seize, take,” graha
“seizing, holding, perceiving” (see also → concept); cf.
M.L.G. grabben “to grab;” E. grab “to take or grasp suddenly;”
PIE base *ghrebh- “to seize”.
