Why do eclipses occur? (1)
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This article explains the geometry of solar and lunar eclipses, explaining such things as why there is not an eclipse every new Moon and why we get annular eclipses. It then moves on to show why eclipses happen at definite intervals and why many eclipses are partial, not total. The historically important Saros period is then described, used in ancient times to predict eclipses. The section on eclipse sequences can be further expanded to explore, in considerable detail, the mechanism that produces such sequences and then expanded again to investigate the strange phenomenon whereby the alignments that produce an eclipse fluctuate with a 565yr periodicity. The section on the Saros period leads on to a major investigation into Saros series and their variability. This article is not for the faint-hearted (!), and so has also been indexed in its own right. Click on the title to read the full article, or on the Saros Series link to read just that article. |
