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A hybrid solar eclipse is a rare, unusual type of solar eclipses in which a total eclipse is seen along some part of the track of the lunar shadow across the surface of our planet and an annular eclipse is seen along the other part(s) of this track. A hybrid solar eclipse is also known as annular-total solar eclipse. Fig (1) The geometry of hybrid solar eclipses
In a hybrid solar eclipse the Moon is at such a critical distance from the Earth that its shadow touches the surface of the Earth in only a part of the eclipse path but fails to strike the planet in the other parts of this track. In these parts it is the antumbral shadow that makes it to the surface of our planet. This is due to the curvature of the Earth's surface; the observers who are physically close enough to the Moon, lie along the track of the lunar umbra. Map (1) The path of the annular-total solar eclipse of 8 April 2005 http://sunearth.gsfc.nasa.gov/eclipse/SEmono/HSE2005/HSE2005fig/HSE2005map1b.GIF Courtesy: Fred Espenak, NASA's GSFC. Consequently, in the part of the path where the eclipse is total, the Moon's apparent size is just big enough to cover up the Sun completely for a total eclipse, and in the other parts, where the observer is farther; from the Moon's apparent size is too small to eclipse the Sun totally and an annular eclipse is seen. The totality and annularity phases of a hybrid solar eclipse are markedly short in duration when compared to the common types of total and annular solar eclipses. In most hybrid solar eclipses, the eclipse track begins as annular then converts into a total eclipse for some part of the track and then becomes annular again till the end of the track. That is, the eclipse is annular on the ends of its path and total in the mid portion. In rarer cases, the hybrid eclipse begins as annular, then converts into a total eclipse till the end of the path, or begins as a total eclipse and then becomes annular for the rest of the path. A notable, recent example of a hybrid solar eclipse is that of 8 April 2005. This eclipse was total across the Pacific (the totality path crossed no island) but was annular in Costa Rica , Columbia and Venezuela . Map (2) The 8 April 2005 hybrid solar eclipse through Costa Rica and Panama http://sunearth.gsfc.nasa.gov/eclipse/SEmono/HSE2005/HSE2005fig/HSE2005map2b.GIF Courtesy: Fred Espenak, NASA's GSFC. Further Reading The Hybrid Solar Eclipse of 8 April 2005 http://sunearth.gsfc.nasa.gov/eclipse/SEmono/HSE2005/HSE2005.html Aymen Mohamed Ibrahem PSC, senior astronomy specialist |
