20th-century annular solar eclipse
An annular solar eclipse occurred at the Moon's descending node of orbit on Thursday, March 17, 1904, with a magnitude of 0.9367. 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. Occurring about 3 days after apogee (on March 14, 1904, at 6:00 UTC), the Moon's apparent diameter was smaller.
The path of annularity covered southern German East Africa (now southern Tanzania), northeastern tip of Portuguese East Africa (now Mozambique), northern Grande Comore Island in French Comoros (now Comoros), southern British Seychelles (now Seychelles), British Mauritius (now Mauritius), most of the British Indian Ocean Territory (excluding the southern part of Diego Garcia), northwestern Sumatra in the Dutch East Indies (now Indonesia), southern Siam (now renamed as Thailand), French Indochina (the part now belonging to Cambodia, the southern tip of Laos and southern Vietnam, including the major city Phnom Penh, now capital of Cambodia), all of the Paracel Islands, the northern tip of the American Philippines (now Philippines) and Japanese islands of Iwo Jima, South Iwo Jima and Minamitorishima.
In addition, a partial solar eclipse was seen within a much larger area, including the eastern half of Africa, southern West Asia, southern Afghanistan, South Asia except the northernmost tip of British Raj (now the northernmost tip of Pakistan), most of China except the northwest border, Korean Peninsula, Japan, Southeast Asia, the extreme northern coast of Australia, northwestern Melanesia, central and western Micronesia, and southeastern Russian Empire.
Observations.
N. Donitch of the Royal Russian Academy of Sciences (the predecessor of today's Russian Academy of Sciences) traveled to Phnom Penh (now capital of Cambodia) via Saigon (now Ho Chi Minh City, Vietnam) in French Indochina and made observations there. The weather was clear on the eclipse day, with only some fog in the morning. Donitch used a spectrometer and recorded changes in the temperature in about 2.5 hours, which dropped for about 3°C.
Eclipse details.
Shown below are two tables displaying details about this particular solar eclipse. The first table outlines times at which the moon's penumbra or umbra attains the specific parameter, and the second table describes various other parameters pertaining to this eclipse.
Eclipse season.
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. The first and last eclipse in this sequence is separated by one synodic month.
Related eclipses.
Solar eclipses of 1902–1906.
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.
The partial solar eclipses on May 7, 1902 and October 31, 1902 occur in the previous lunar year eclipse set, and the partial solar eclipse on July 21, 1906 occurs in the next lunar year eclipse set.
Saros 128.
This eclipse is a part of Saros series 128, repeating every 18 years, 11 days, and containing 73 events. The series started with a partial solar eclipse on August 29, 984 AD. It contains total eclipses from May 16, 1417 through June 18, 1471; hybrid eclipses from June 28, 1489 through July 31, 1543; and annular eclipses from August 11, 1561 through July 25, 2120. The series ends at member 73 as a partial eclipse on November 1, 2282. 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 totality was produced by member 27 at 1 minutes, 45 seconds on June 7, 1453, and the longest duration of annularity was produced by member 48 at 8 minutes, 35 seconds on February 1, 1832. All eclipses in this series occur at the Moon’s descending node of orbit.
Metonic series.
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.
Tritos series.
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.
Inex series.
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.
Notes.
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