January 1973 lunar eclipse

A penumbral lunar eclipse occurred at the Moon’s descending node of orbit on Thursday, January 18, 1973, with an umbral magnitude of −0.1292. A lunar eclipse occurs when the Moon moves into the Earth's shadow, causing the Moon to be darkened. A penumbral lunar eclipse occurs when part or all of the Moon's near side passes into the Earth's penumbra. Unlike a solar eclipse, which can only be viewed from a relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of Earth. Occurring about 2 days after perigee (on January 16, 1973, at 20:50 UTC), the Moon's apparent diameter was larger.

This eclipse was the first of four lunar eclipses in 1973, with the others occurring on June 15 (penumbral), July 15 (penumbral), and December 10 (partial).

Visibility

The eclipse was completely visible over Europe, Africa, and Asia, seen rising over eastern North America and much of South America and setting over east Asia and Australia.

Eclipse details

Shown below is a table displaying details about this particular solar eclipse. It describes various 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.

Related eclipses

Eclipses in 1973

• An annular solar eclipse on January 4.
• A penumbral lunar eclipse on January 18.
• A penumbral lunar eclipse on June 15.
• A total solar eclipse on June 30.
• A penumbral lunar eclipse on July 15.
• A partial lunar eclipse on December 10.
• An annular solar eclipse on December 24.

Metonic

• Preceded by: Lunar eclipse of April 2, 1969
• Followed by: Lunar eclipse of November 6, 1976

Tzolkinex

• Preceded by: Lunar eclipse of December 8, 1965
• Followed by: Lunar eclipse of March 1, 1980

Half-Saros

• Preceded by: Solar eclipse of January 14, 1964
• Followed by: Solar eclipse of January 25, 1982

Tritos

• Preceded by: Lunar eclipse of February 19, 1962
• Followed by: Lunar eclipse of December 20, 1983

Lunar Saros 143

• Preceded by: Lunar eclipse of January 8, 1955
• Followed by: Lunar eclipse of January 30, 1991

Inex

• Preceded by: Lunar eclipse of February 9, 1944
• Followed by: Lunar eclipse of December 30, 2001

Triad

• Preceded by: Lunar eclipse of March 20, 1886
• Followed by: Lunar eclipse of November 19, 2059

Lunar eclipses of 1969–1973

This eclipse is a member of a semester series. An eclipse in a semester series of lunar eclipses repeats approximately every 177 days and 4 hours (a semester) at alternating nodes of the Moon's orbit.

The penumbral lunar eclipses on April 2, 1969 and September 25, 1969 occur in the previous lunar year eclipse set, and the lunar eclipses on June 15, 1973 (penumbral) and December 10, 1973 (partial) occur in the next lunar year eclipse set.

Saros 143

This eclipse is a part of Saros series 143, repeating every 18 years, 11 days, and containing 72 events. The series started with a penumbral lunar eclipse on August 18, 1720. It contains partial eclipses from March 14, 2063 through June 21, 2225; total eclipses from July 2, 2243 through April 13, 2712; and a second set of partial eclipses from April 25, 2730 through July 9, 2856. The series ends at member 72 as a penumbral eclipse on October 5, 3000.

The longest duration of totality will be produced by member 36 at 99 minutes, 9 seconds on September 6, 2351. All eclipses in this series occur at the Moon’s descending node of orbit.

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.

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.

Half-Saros cycle

A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days (a half saros). This lunar eclipse is related to two partial solar eclipses of Solar Saros 150.

See also

• List of lunar eclipses
• List of 20th-century lunar eclipses

Notes

External links

• Eclipse Predictions by Fred Espenak, NASA/GSFC