Solar eclipses with very similar characteristics repeat every 6,585.3 days (18 years 11 days 8 hours). This is the so-called Saros cycle, first discovered by Babylonian astronomers more than two millennia ago.
Any two eclipses separated by one Saros period occur at the same time of year with the Moon at the same node, and at nearly the same distance from Earth. This makes the Saros a useful tool for organizing eclipses into groups or series. Although the geometry of each eclipse in a Saros series is quite similar, it’s not identical. Each series typically lasts about 13 centuries and contains approximately 70 eclipses.
The August 1, 2008, total solar eclipse is the 47th in a series of 72 eclipses belonging to Saros 126.
The series began in 1179 with a small partial eclipse from Antarctica. The next seven eclipses were also partial as the Moon's umbra passed closer to Earth with each event. The first 28 central eclipses of Saros 126 were all annular (ring eclipses) with the duration of annularity steadily decreasing during each eclipse. Three annular-total “hybrid” eclipses followed in 1828, 1846, and 1864. The series didn't produce its first purely total eclipse until May 17, 1882.
Throughout the 19th and 20th centuries, Saros 126 continued to produce total eclipses with increasing durations. Long-time amateur astronomers may remember the last two members. The July 10, 1972, eclipse lasted 2
Saros 126 is now a series in old age. After 2008, it will produce only two more total eclipses in 2026 (Greenland, Portugal, and Spain) and 2044 (Canada and the north-central US). After that, the series will dwindle with a long sequence of 23 partial eclipses. The final eclipse occurs in 2459, 1,280 years after the series began.