An annular solar eclipse occurred at the Moon's descending node of orbit on Friday, December 14, 2001,[1][2][3][4] with a magnitude of 0.9681. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide. The Moon's apparent diameter was near the average diameter because it occurred 7.9 days after perigee (on December 6, 2001, at 22:40 UTC) and 6.7 days before apogee (on December 21, 2001, at 13:00 UTC).[5]
The path of annularity was mostly on the sea, so observers were concentrated in Central America, the only land covered by the path, especially in Costa Rica with the largest area covered by the path and highest solar zenith angle. However, it was cloudy or rainy in many parts of the country during the eclipse, and only a few observers saw the annular eclipse.[6] The International Occultation Timing Association made up of scientists from different countries planned to measure the diameter of the sun with Baily's beads that appeared at the moment of the second and third contacts in Santa Rosa National Park on the northern edge of the path of annularity, but failed.[7] A team of professors from the University of Costa Rica and abroad traveled to Ostional Mixed Wildlife Refuge, kilometres north of Nosara. The sun could be seen through the clouds after the eclipse started, but it was completely clouded out when 80% was blocked by the moon. All the stages after that, including the annularity, could not be seen.[8]
Coincidentally, the 2001 Geminids peaked in the early morning of December 14 local time, less than 24 hours before the annular solar eclipse.[7]
This eclipse is part of an eclipse season, a period, roughly every six months, when eclipses occur. Only two (or occasionally three) eclipse seasons occur each year, and each season lasts about 35 days and repeats just short of six months (173 days) later; thus two full eclipse seasons always occur each year. Either two or three eclipses happen each eclipse season. In the sequence below, each eclipse is separated by a fortnight.
This eclipse is a member of a semester series. An eclipse in a semester series of solar eclipses repeats approximately every 177 days and 4 hours (a semester) at alternating nodes of the Moon's orbit.[9]
This eclipse is a part of Saros series 132, repeating every 18 years, 11 days, and containing 71 events. The series started with a partial solar eclipse on August 13, 1208. It contains annular eclipses from March 17, 1569 through March 12, 2146; hybrid eclipses on March 23, 2164 and April 3, 2182; and total eclipses from April 14, 2200 through June 19, 2308. The series ends at member 71 as a partial eclipse on September 25, 2470. Its eclipses are tabulated in three columns; every third eclipse in the same column is one exeligmos apart, so they all cast shadows over approximately the same parts of the Earth.
The longest duration of annularity was produced by member 25 at 6 minutes, 56 seconds on May 9, 1641, and the longest duration of totality will be produced by member 61 at 2 minutes, 14 seconds on June 8, 2290. All eclipses in this series occur at the Moon’s descending node of orbit.[10]
The metonic series repeats eclipses every 19 years (6939.69 days), lasting about 5 cycles. Eclipses occur in nearly the same calendar date. In addition, the octon subseries repeats 1/5 of that or every 3.8 years (1387.94 days). All eclipses in this table occur at the Moon's descending node.
21 eclipse events between July 22, 1971 and July 22, 2047
This eclipse is a part of a tritos cycle, repeating at alternating nodes every 135 synodic months (≈ 3986.63 days, or 11 years minus 1 month). Their appearance and longitude are irregular due to a lack of synchronization with the anomalistic month (period of perigee), but groupings of 3 tritos cycles (≈ 33 years minus 3 months) come close (≈ 434.044 anomalistic months), so eclipses are similar in these groupings.
This eclipse is a part of the long period inex cycle, repeating at alternating nodes, every 358 synodic months (≈ 10,571.95 days, or 29 years minus 20 days). Their appearance and longitude are irregular due to a lack of synchronization with the anomalistic month (period of perigee). However, groupings of 3 inex cycles (≈ 87 years minus 2 months) comes close (≈ 1,151.02 anomalistic months), so eclipses are similar in these groupings.
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