Solar eclipse of April 28, 1911

A team of Stonyhurst College, England and Saint Ignatius' College, Riverview, New South Wales made observations in Vavaʻu Islands, Tonga. Members of Stonyhurst College departed from Tilbury, England by ship on February 3 and arrived in Sydney on March 16. The team later departed from Sydney on March 25 and arrived in Vavaʻu on April 2. All the instruments were shipped ashore on April 5. The weather was clear for the next few days, but heavy rain showers fell almost every day starting from April 10. The southeast wind starting on April 26 brought thick and large cirrus clouds. On April 28, one day before the eclipse, there were many clouds, which lasted until the morning of April 29. On April 29, the eclipse day, the sky cleared before the first contact (beginning of the partial phase). Afterwards, some cumulus clouds passed through at first, and the weather remained relatively good. During the totality, weather conditions were good in Neiafu, but some areas about 2 miles (3.2 km) away were affected by cirrostratus clouds, and the sun was not visible until 90 seconds before the third contact (end of the total phase). During the eclipse, there was almost no sound on the island except the chirping of crickets, because the government told the local people to keep quiet and not to light fires to avoid creating smoke and disturbing the observations. The team shipped the instruments back on May 2, and the team members departed the island on May 4. They first arrived in Suva, capital of the Colony of Fiji on May 6, and departed again on May 11 and arrived in Sydney on May 17. The British in charge boarded the ship with the instruments leaving Sydney on June 10 and arriving in Tilbury on July 23.^[6]

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.^[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.

• A total solar eclipse on April 28.
• A penumbral lunar eclipse on May 13.
• An annular solar eclipse on October 22.
• A penumbral lunar eclipse on November 6.

• Preceded by: Solar eclipse of July 10, 1907
• Followed by: Solar eclipse of February 14, 1915

• Preceded by: Solar eclipse of March 17, 1904
• Followed by: Solar eclipse of June 8, 1918

• Preceded by: Lunar eclipse of April 22, 1902
• Followed by: Lunar eclipse of May 3, 1920

• Preceded by: Solar eclipse of May 28, 1900
• Followed by: Solar eclipse of March 28, 1922

• Preceded by: Solar eclipse of April 16, 1893
• Followed by: Solar eclipse of May 9, 1929

• Preceded by: Solar eclipse of May 17, 1882
• Followed by: Solar eclipse of April 7, 1940

• Preceded by: Solar eclipse of June 26, 1824
• Followed by: Solar eclipse of February 26, 1998

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.^[8]

The partial solar eclipse on August 31, 1913 occurs in the next lunar year eclipse set.

This eclipse is a part of Saros series 127, repeating every 18 years, 11 days, and containing 82 events. The series started with a partial solar eclipse on October 10, 991 AD. It contains total eclipses from May 14, 1352 through August 15, 2091. There are no annular or hybrid eclipses in this set. The series ends at member 82 as a partial eclipse on March 21, 2452. 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 31 at 5 minutes, 40 seconds on August 30, 1532. All eclipses in this series occur at the Moon’s ascending node of orbit.^[9]

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 ascending node.

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.

• HMAS Encounter (1902)#Operational history

• NASA graphics
• Report on the total solar eclipse of 1911, April 28 Tonga Island, South Pacific