A Spectacular Solar Eclipse
A Solar Eclipse is perhaps the most impressive of all astronomical events, and we owe it all to fortuitous coincidence. Once about every six months the Moon passes directly between Earth and the Sun. The coincidence is that although the Sun is about four hundred times larger than the Moon, it is also about four hundred times farther away, so the two objects appear nearly the same size in our sky. As a result, during a total eclipse the Moon just covers the solar disk.
When that happens, the Moon casts a shadow of Earth’s surface. Unfortunately, the shadow covers only a narrow strip of Earth. For those in the path of the shadow, the early partial phases of the eclipse are mere prelude. In the seconds just before the Sun is completely engulfed, viewers see the last vestiges of the Sun’s light peeking between mountain peaks on the Moon’s limb, a phenomenon known as Baily’s Beads. During totality stars pop into view as the sky is plunged into near-darkness.
When the eclipse arrives, for those who have always wanted to visit a country where it can be seen,, but never had a good excuse, this moment is a great time to go. For instance, on July 11, 1991, Hawaii was one of two prime observing spots for what was the best solar eclipse in the 1990s. The July 11, eclipse began in the Pacific Ocean west of Hawaii and moved ashore on the Big Island about 7.30 a.m. local time. At 11.45 a.m. the shadow crossed the southern tip of Baja California. Totality lasted almost seven minutes there – nearly the maximum length of time possible for a total eclipse. The Moon’s shadow raced on through central and southern Mexico, down the Pacific coast of Central America, and into Colombia. Finally it crossed into the Brazilian rain forest and then left Earth just short of the Atlantic Ocean.
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