# January 1991 lunar eclipse

A penumbral lunar eclipse occurred at the Moon’s descending node of orbit on Wednesday, January 30, 1991, with an umbral magnitude of −0.1106. 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 1.9 days after perigee (on January 28, 1991, at 8:35 UTC), the Moon's apparent diameter was larger.
This eclipse was the first of four lunar eclipses in 1991, with the others occurring on June 27 (penumbral), July 26 (penumbral), and December 21 (partial).

## Visibility

The eclipse was completely visible over North and South America, seen rising over northeast Asia and the central Pacific Ocean and setting over much of Africa and Europe.

## Eclipse details

Shown below is a table displaying details about this particular solar eclipse. It describes various parameters pertaining to this eclipse.
January 30, 1991 Lunar Eclipse Parameters :
| Parameter | Value |
| Penumbral Magnitude | 0.88079 |
| Umbral Magnitude | −0.11060 |
| Gamma | −1.07522 |
| Sun Right Ascension | 20h49m07.1s |
| Sun Declination | -17°47'12.6" |
| Sun Semi-Diameter | 16'14.2" |
| Sun Equatorial Horizontal Parallax | 08.9" |
| Moon Right Ascension | 08h47m30.0s |
| Moon Declination | +16°46'53.1" |
| Moon Semi-Diameter | 16'22.7" |
| Moon Equatorial Horizontal Parallax | 1°00'06.5" |
| ΔT | 57.6 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 January 1991 :
| January 15 Ascending node (new moon) | January 30 Descending node (full moon) |
| Annular solar eclipse Solar Saros 131 | Penumbral lunar eclipse Lunar Saros 143 |

## Related eclipses
### Eclipses in 1991

* An annular solar eclipse on January 15.
* A penumbral lunar eclipse on January 30.
* A penumbral lunar eclipse on June 27.
* A total solar eclipse on July 11.
* A penumbral lunar eclipse on July 26.
* A partial lunar eclipse on December 21.

### Metonic

* Preceded by: Lunar eclipse of April 14, 1987
* Followed by: Lunar eclipse of November 18, 1994

### Tzolkinex

* Preceded by: Lunar eclipse of December 20, 1983
* Followed by: Lunar eclipse of March 13, 1998

### Half-Saros

* Preceded by: Solar eclipse of January 25, 1982
* Followed by: Solar eclipse of February 5, 2000

### Tritos

* Preceded by: Lunar eclipse of March 1, 1980
* Followed by: Lunar eclipse of December 30, 2001

### Lunar Saros 143

* Preceded by: Lunar eclipse of January 18, 1973
* Followed by: Lunar eclipse of February 9, 2009

### Inex

* Preceded by: Lunar eclipse of February 19, 1962
* Followed by: Lunar eclipse of January 10, 2020

### Triad

* Preceded by: Lunar eclipse of March 31, 1904
* Followed by: Lunar eclipse of November 29, 2077

### Lunar eclipses of 1988–1991

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 lunar eclipses on June 27, 1991 (penumbral) and December 21, 1991 (partial) occur in the next lunar year eclipse set.
Lunar eclipse series sets from 1988 to 1991 :
| Descending node | Descending node | Descending node | Descending node | Ascending node | Ascending node | Ascending node | Ascending node |
| Saros | Date Viewing | Type Chart | Gamma | Saros | Date Viewing | Type Chart | Gamma |
| 113 | 1988 Mar 03 | Penumbral | 0.9886 | 118 | 1988 Aug 27 | Partial | −0.8682 |
| 123 | 1989 Feb 20 | Total | 0.2935 | 128 | 1989 Aug 17 | Total | −0.1491 |
| 133 | 1990 Feb 09 | Total | −0.4148 | 138 | 1990 Aug 06 | Partial | 0.6374 |
| 143 | 1991 Jan 30 | Penumbral | −1.0752 | 148 | 1991 Jul 26 | Penumbral | 1.4370 |

### 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.
| Greatest | First | First | First | First |
| The greatest eclipse of the series will occur on 2351 Sep 06, lasting 99 minutes, 9 seconds. | Penumbral | Partial | Total | Central |
| The greatest eclipse of the series will occur on 2351 Sep 06, lasting 99 minutes, 9 seconds. | 1720 Aug 18 | 2063 Mar 14 | 2243 Jul 02 | 2297 Aug 03 |
| Last ||||
| The greatest eclipse of the series will occur on 2351 Sep 06, lasting 99 minutes, 9 seconds. | Central | Total | Partial | Penumbral |
| The greatest eclipse of the series will occur on 2351 Sep 06, lasting 99 minutes, 9 seconds. | 2495 Dec 02 | 2712 Apr 13 | 2856 Jul 09 | 3000 Oct 05 |
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 6–27 occur between 1801 and 2200: :
| 6 | 6 | 7 | 7 | 8 | 8 |
| 1810 Oct 12 | 1810 Oct 12 | 1828 Oct 23 | 1828 Oct 23 | 1846 Nov 03 | 1846 Nov 03 |
| 9 | 9 | 10 | 10 | 11 | 11 |
| 1864 Nov 13 | 1864 Nov 13 | 1882 Nov 25 | 1882 Nov 25 | 1900 Dec 06 | 1900 Dec 06 |
| 12 | 12 | 13 | 13 | 14 | 14 |
| 1918 Dec 17 | 1918 Dec 17 | 1936 Dec 28 | 1936 Dec 28 | 1955 Jan 08 | 1955 Jan 08 |
| 15 | 15 | 16 | 16 | 17 | 17 |
| 1973 Jan 18 | 1973 Jan 18 | 1991 Jan 30 | 1991 Jan 30 | 2009 Feb 09 | 2009 Feb 09 |
| 18 | 18 | 19 | 19 | 20 | 20 |
| 2027 Feb 20 | 2027 Feb 20 | 2045 Mar 03 | 2045 Mar 03 | 2063 Mar 14 | 2063 Mar 14 |
| 21 | 21 | 22 | 22 | 23 | 23 |
| 2081 Mar 25 | 2081 Mar 25 | 2099 Apr 05 | 2099 Apr 05 | 2117 Apr 16 | 2117 Apr 16 |
| 24 | 24 | 25 | 25 | 26 | 26 |
| 2135 Apr 28 | 2135 Apr 28 | 2153 May 08 | 2153 May 08 | 2171 May 19 | 2171 May 19 |
| 27 ||
| 2189 May 29 ||

### 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 2132 :
| 1805 Jul 11 (Saros 126) | 1805 Jul 11 (Saros 126) | 1816 Jun 10 (Saros 127) | 1816 Jun 10 (Saros 127) | 1827 May 11 (Saros 128) | 1827 May 11 (Saros 128) | 1838 Apr 10 (Saros 129) | 1838 Apr 10 (Saros 129) | 1849 Mar 09 (Saros 130) | 1849 Mar 09 (Saros 130) |
| 1860 Feb 07 (Saros 131) | 1860 Feb 07 (Saros 131) | 1871 Jan 06 (Saros 132) | 1871 Jan 06 (Saros 132) | 1881 Dec 05 (Saros 133) | 1881 Dec 05 (Saros 133) | 1892 Nov 04 (Saros 134) | 1892 Nov 04 (Saros 134) | 1903 Oct 06 (Saros 135) | 1903 Oct 06 (Saros 135) |
| 1914 Sep 04 (Saros 136) | 1914 Sep 04 (Saros 136) | 1925 Aug 04 (Saros 137) | 1925 Aug 04 (Saros 137) | 1936 Jul 04 (Saros 138) | 1936 Jul 04 (Saros 138) | 1947 Jun 03 (Saros 139) | 1947 Jun 03 (Saros 139) | 1958 May 03 (Saros 140) | 1958 May 03 (Saros 140) |
| 1969 Apr 02 (Saros 141) | 1969 Apr 02 (Saros 141) | 1980 Mar 01 (Saros 142) | 1980 Mar 01 (Saros 142) | 1991 Jan 30 (Saros 143) | 1991 Jan 30 (Saros 143) | 2001 Dec 30 (Saros 144) | 2001 Dec 30 (Saros 144) | 2012 Nov 28 (Saros 145) | 2012 Nov 28 (Saros 145) |
| 2023 Oct 28 (Saros 146) | 2023 Oct 28 (Saros 146) | 2034 Sep 28 (Saros 147) | 2034 Sep 28 (Saros 147) | 2045 Aug 27 (Saros 148) | 2045 Aug 27 (Saros 148) | 2056 Jul 26 (Saros 149) | 2056 Jul 26 (Saros 149) | 2067 Jun 27 (Saros 150) | 2067 Jun 27 (Saros 150) |
| 2132 Dec 22 (Saros 156) ||

### 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 :
| 1817 May 30 (Saros 137) | 1817 May 30 (Saros 137) | 1846 May 11 (Saros 138) | 1846 May 11 (Saros 138) | 1875 Apr 20 (Saros 139) | 1875 Apr 20 (Saros 139) |
| 1904 Mar 31 (Saros 140) | 1904 Mar 31 (Saros 140) | 1933 Mar 12 (Saros 141) | 1933 Mar 12 (Saros 141) | 1962 Feb 19 (Saros 142) | 1962 Feb 19 (Saros 142) |
| 1991 Jan 30 (Saros 143) | 1991 Jan 30 (Saros 143) | 2020 Jan 10 (Saros 144) | 2020 Jan 10 (Saros 144) | 2048 Dec 20 (Saros 145) | 2048 Dec 20 (Saros 145) |
| 2077 Nov 29 (Saros 146) | 2077 Nov 29 (Saros 146) | 2106 Nov 11 (Saros 147) | 2106 Nov 11 (Saros 147) | 2135 Oct 22 (Saros 148) | 2135 Oct 22 (Saros 148) |
| 2164 Sep 30 (Saros 149) | 2164 Sep 30 (Saros 149) | 2193 Sep 11 (Saros 150) | 2193 Sep 11 (Saros 150) |

### 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.
| January 25, 1982 | February 5, 2000 |