# December 1973 lunar eclipse

A partial lunar eclipse occurred at the Moon’s descending node of orbit on Monday, December 10, 1973, with an umbral magnitude of 0.1007. A lunar eclipse occurs when the Moon moves into the Earth's shadow, causing the Moon to be darkened. A partial lunar eclipse occurs when one part of the Moon is in the Earth's umbra, while the other part is in 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 only about 21 hours before perigee (on December 10, 1973, at 22:20 UTC), the Moon's apparent diameter was larger.
This eclipse was the last of four lunar eclipses in 1973, with the others occurring on January 18 (penumbral), June 15 (penumbral), and July 15 (penumbral).

## Visibility

The eclipse was completely visible over much of North and South America, Africa, Europe, and west and north Asia, seen rising over western North America and the eastern Pacific Ocean and setting over southeast Africa and much of Asia.

## Eclipse details

Shown below is a table displaying details about this particular solar eclipse. It describes various parameters pertaining to this eclipse.
December 10, 1973 Lunar Eclipse Parameters :
| Parameter | Value |
| Penumbral Magnitude | 1.07597 |
| Umbral Magnitude | 0.10069 |
| Gamma | 0.96441 |
| Sun Right Ascension | 17h07m12.8s |
| Sun Declination | -22°53'16.9" |
| Sun Semi-Diameter | 16'14.5" |
| Sun Equatorial Horizontal Parallax | 08.9" |
| Moon Right Ascension | 05h07m14.5s |
| Moon Declination | +23°52'13.3" |
| Moon Semi-Diameter | 16'39.2" |
| Moon Equatorial Horizontal Parallax | 1°01'07.2" |
| ΔT | 44.3 s |

## 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.
Eclipse season of December 1973 :
| December 10 Descending node (full moon) | December 24 Ascending node (new moon) |
| Partial lunar eclipse Lunar Saros 115 | Annular solar eclipse Solar Saros 141 |

## 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 February 21, 1970
* Followed by: Lunar eclipse of September 27, 1977

### Tzolkinex

* Preceded by: Lunar eclipse of October 29, 1966
* Followed by: Lunar eclipse of January 20, 1981

### Half-Saros

* Preceded by: Solar eclipse of December 4, 1964
* Followed by: Solar eclipse of December 15, 1982

### Tritos

* Preceded by: Lunar eclipse of January 9, 1963
* Followed by: Lunar eclipse of November 8, 1984

### Lunar Saros 115

* Preceded by: Lunar eclipse of November 29, 1955
* Followed by: Lunar eclipse of December 21, 1991

### Inex

* Preceded by: Lunar eclipse of December 29, 1944
* Followed by: Lunar eclipse of November 20, 2002

### Triad

* Preceded by: Lunar eclipse of February 8, 1887
* Followed by: Lunar eclipse of October 9, 2060

### Lunar eclipses of 1973–1976

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 January 18, 1973 and July 15, 1973 occur in the previous lunar year eclipse set.
Lunar eclipse series sets from 1973 to 1976 :
| Ascending node | Ascending node | Ascending node | Ascending node | Descending node | Descending node | Descending node | Descending node |
| Saros | Date Viewing | Type Chart | Gamma | Saros | Date Viewing | Type Chart | Gamma |
| 110 | 1973 Jun 15 | Penumbral | −1.3217 | 115 | 1973 Dec 10 | Partial | 0.9644 |
| 120 | 1974 Jun 04 | Partial | −0.5489 | 125 | 1974 Nov 29 | Total | 0.3054 |
| 130 | 1975 May 25 | Total | 0.2367 | 135 | 1975 Nov 18 | Total | −0.4134 |
| 140 | 1976 May 13 | Partial | 0.9586 | 145 | 1976 Nov 06 | Penumbral | −1.1276 |

### Saros 115

This eclipse is a part of Saros series 115, repeating every 18 years, 11 days, and containing 72 events. The series started with a penumbral lunar eclipse on April 21, 1000. It contains partial eclipses from July 6, 1126 through September 30, 1270; total eclipses from October 11, 1288 through July 20, 1739; and a second set of partial eclipses from July 30, 1757 through February 13, 2082. The series ends at member 72 as a penumbral eclipse on June 13, 2280.
The longest duration of totality was produced by member 36 at 99 minutes, 47 seconds on May 15, 1631. All eclipses in this series occur at the Moon’s descending node of orbit.
| Greatest | First | First | First | First |
| The greatest eclipse of the series occurred on 1631 May 15, lasting 99 minutes, 47 seconds. | Penumbral | Partial | Total | Central |
| The greatest eclipse of the series occurred on 1631 May 15, lasting 99 minutes, 47 seconds. | 1000 Apr 21 | 1126 Jul 06 | 1288 Oct 11 | 1541 Mar 12 |
| Last ||||
| The greatest eclipse of the series occurred on 1631 May 15, lasting 99 minutes, 47 seconds. | Central | Total | Partial | Penumbral |
| The greatest eclipse of the series occurred on 1631 May 15, lasting 99 minutes, 47 seconds. | 1685 Jun 16 | 1739 Jul 20 | 2082 Feb 13 | 2280 Jun 13 |
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.
Series members 46–67 occur between 1801 and 2200: :
| 46 | 46 | 47 | 47 | 48 | 48 |
| 1811 Sep 02 | 1811 Sep 02 | 1829 Sep 13 | 1829 Sep 13 | 1847 Sep 24 | 1847 Sep 24 |
| 49 | 49 | 50 | 50 | 51 | 51 |
| 1865 Oct 04 | 1865 Oct 04 | 1883 Oct 16 | 1883 Oct 16 | 1901 Oct 27 | 1901 Oct 27 |
| 52 | 52 | 53 | 53 | 54 | 54 |
| 1919 Nov 07 | 1919 Nov 07 | 1937 Nov 18 | 1937 Nov 18 | 1955 Nov 29 | 1955 Nov 29 |
| 55 | 55 | 56 | 56 | 57 | 57 |
| 1973 Dec 10 | 1973 Dec 10 | 1991 Dec 21 | 1991 Dec 21 | 2009 Dec 31 | 2009 Dec 31 |
| 58 | 58 | 59 | 59 | 60 | 60 |
| 2028 Jan 12 | 2028 Jan 12 | 2046 Jan 22 | 2046 Jan 22 | 2064 Feb 02 | 2064 Feb 02 |
| 61 | 61 | 62 | 62 | 63 | 63 |
| 2082 Feb 13 | 2082 Feb 13 | 2100 Feb 24 | 2100 Feb 24 | 2118 Mar 07 | 2118 Mar 07 |
| 64 | 64 | 65 | 65 | 66 | 66 |
| 2136 Mar 18 | 2136 Mar 18 | 2154 Mar 29 | 2154 Mar 29 | 2172 Apr 09 | 2172 Apr 09 |
| 67 ||
| 2190 Apr 20 ||

### 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.
Series members between 1801 and 2200 :
| 1810 Mar 21 (Saros 100) | 1810 Mar 21 (Saros 100) | 1821 Feb 17 (Saros 101) | 1821 Feb 17 (Saros 101) | 1832 Jan 17 (Saros 102) | 1832 Jan 17 (Saros 102) | 1842 Dec 17 (Saros 103) | 1842 Dec 17 (Saros 103) | | |
| 1864 Oct 15 (Saros 105) | 1864 Oct 15 (Saros 105) | 1875 Sep 15 (Saros 106) | 1875 Sep 15 (Saros 106) | 1886 Aug 14 (Saros 107) | 1886 Aug 14 (Saros 107) | 1897 Jul 14 (Saros 108) | 1897 Jul 14 (Saros 108) | 1908 Jun 14 (Saros 109) | 1908 Jun 14 (Saros 109) |
| 1919 May 15 (Saros 110) | 1919 May 15 (Saros 110) | 1930 Apr 13 (Saros 111) | 1930 Apr 13 (Saros 111) | 1941 Mar 13 (Saros 112) | 1941 Mar 13 (Saros 112) | 1952 Feb 11 (Saros 113) | 1952 Feb 11 (Saros 113) | 1963 Jan 09 (Saros 114) | 1963 Jan 09 (Saros 114) |
| 1973 Dec 10 (Saros 115) | 1973 Dec 10 (Saros 115) | 1984 Nov 08 (Saros 116) | 1984 Nov 08 (Saros 116) | 1995 Oct 08 (Saros 117) | 1995 Oct 08 (Saros 117) | 2006 Sep 07 (Saros 118) | 2006 Sep 07 (Saros 118) | 2017 Aug 07 (Saros 119) | 2017 Aug 07 (Saros 119) |
| 2028 Jul 06 (Saros 120) | 2028 Jul 06 (Saros 120) | 2039 Jun 06 (Saros 121) | 2039 Jun 06 (Saros 121) | 2050 May 06 (Saros 122) | 2050 May 06 (Saros 122) | 2061 Apr 04 (Saros 123) | 2061 Apr 04 (Saros 123) | 2072 Mar 04 (Saros 124) | 2072 Mar 04 (Saros 124) |
| 2083 Feb 02 (Saros 125) | 2083 Feb 02 (Saros 125) | 2094 Jan 01 (Saros 126) | 2094 Jan 01 (Saros 126) | 2104 Dec 02 (Saros 127) | 2104 Dec 02 (Saros 127) | 2115 Nov 02 (Saros 128) | 2115 Nov 02 (Saros 128) | 2126 Oct 01 (Saros 129) | 2126 Oct 01 (Saros 129) |
| 2137 Aug 30 (Saros 130) | 2137 Aug 30 (Saros 130) | 2148 Jul 31 (Saros 131) | 2148 Jul 31 (Saros 131) | 2159 Jun 30 (Saros 132) | 2159 Jun 30 (Saros 132) | 2170 May 30 (Saros 133) | 2170 May 30 (Saros 133) | 2181 Apr 29 (Saros 134) | 2181 Apr 29 (Saros 134) |
| 2192 Mar 28 (Saros 135) ||

### 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.
Series members between 1801 and 2200 :
| 1829 Mar 20 (Saros 110) | 1829 Mar 20 (Saros 110) | 1858 Feb 27 (Saros 111) | 1858 Feb 27 (Saros 111) | 1887 Feb 08 (Saros 112) | 1887 Feb 08 (Saros 112) |
| 1916 Jan 20 (Saros 113) | 1916 Jan 20 (Saros 113) | 1944 Dec 29 (Saros 114) | 1944 Dec 29 (Saros 114) | 1973 Dec 10 (Saros 115) | 1973 Dec 10 (Saros 115) |
| 2002 Nov 20 (Saros 116) | 2002 Nov 20 (Saros 116) | 2031 Oct 30 (Saros 117) | 2031 Oct 30 (Saros 117) | 2060 Oct 09 (Saros 118) | 2060 Oct 09 (Saros 118) |
| 2089 Sep 19 (Saros 119) | 2089 Sep 19 (Saros 119) | 2118 Aug 31 (Saros 120) | 2118 Aug 31 (Saros 120) | 2147 Aug 11 (Saros 121) | 2147 Aug 11 (Saros 121) |
| 2176 Jul 21 (Saros 122) ||

### 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 122.
| December 4, 1964 | December 15, 1982 |