# August 1990 lunar eclipse

A partial lunar eclipse occurred at the Moon’s ascending node of orbit on Monday, August 6, 1990, with an umbral magnitude of 0.6766. 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 about 6.2 days after apogee (on July 31, 1990, at 9:20 UTC), the Moon's apparent diameter was smaller.

## Visibility

The eclipse was completely visible over east Asia, Australia, and Antarctica, seen rising over much of Asia and east Africa and setting over western North America and the eastern Pacific Ocean.

## Eclipse details

Shown below is a table displaying details about this particular solar eclipse. It describes various parameters pertaining to this eclipse.
August 6, 1990 Lunar Eclipse Parameters :
| Parameter | Value |
| Penumbral Magnitude | 1.70047 |
| Umbral Magnitude | 0.67658 |
| Gamma | 0.63741 |
| Sun Right Ascension | 09h05m18.6s |
| Sun Declination | +16°40'08.3" |
| Sun Semi-Diameter | 15'46.2" |
| Sun Equatorial Horizontal Parallax | 08.7" |
| Moon Right Ascension | 21h04m21.5s |
| Moon Declination | -16°06'49.0" |
| Moon Semi-Diameter | 15'24.1" |
| Moon Equatorial Horizontal Parallax | 0°56'31.6" |
| ΔT | 57.3 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 July–August 1990 :
| July 22 Descending node (new moon) | August 6 Ascending node (full moon) |
| Total solar eclipse Solar Saros 126 | Partial lunar eclipse Lunar Saros 138 |

## Related eclipses
### Eclipses in 1990

* An annular solar eclipse on January 26.
* A total lunar eclipse on February 9.
* A total solar eclipse on July 22.
* A partial lunar eclipse on August 6.

### Metonic

* Preceded by: Lunar eclipse of October 17, 1986
* Followed by: Lunar eclipse of May 25, 1994

### Tzolkinex

* Preceded by: Lunar eclipse of June 25, 1983
* Followed by: Lunar eclipse of September 16, 1997

### Half-Saros

* Preceded by: Solar eclipse of July 31, 1981
* Followed by: Solar eclipse of August 11, 1999

### Tritos

* Preceded by: Lunar eclipse of September 6, 1979
* Followed by: Lunar eclipse of July 5, 2001

### Lunar Saros 138

* Preceded by: Lunar eclipse of July 26, 1972
* Followed by: Lunar eclipse of August 16, 2008

### Inex

* Preceded by: Lunar eclipse of August 26, 1961
* Followed by: Lunar eclipse of July 16, 2019

### Triad

* Preceded by: Lunar eclipse of October 6, 1903
* Followed by: Lunar eclipse of June 6, 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 138

This eclipse is a part of Saros series 138, repeating every 18 years, 11 days, and containing 82 events. The series started with a penumbral lunar eclipse on October 15, 1521. It contains partial eclipses from June 24, 1918 through August 28, 2026; total eclipses from September 7, 2044 through June 8, 2495; and a second set of partial eclipses from June 19, 2513 through August 13, 2603. The series ends at member 82 as a penumbral eclipse on March 30, 2982.
The longest duration of totality will be produced by member 48 at 105 minutes, 24 seconds on March 24, 2369. All eclipses in this series occur at the Moon’s ascending node of orbit.
| Greatest | First | First | First | First |
| The greatest eclipse of the series will occur on 2369 Mar 24, lasting 105 minutes, 24 seconds. | Penumbral | Partial | Total | Central |
| The greatest eclipse of the series will occur on 2369 Mar 24, lasting 105 minutes, 24 seconds. | 1521 Oct 15 | 1918 Jun 24 | 2044 Sep 07 | 2116 Oct 21 |
| Last ||||
| The greatest eclipse of the series will occur on 2369 Mar 24, lasting 105 minutes, 24 seconds. | Central | Total | Partial | Penumbral |
| The greatest eclipse of the series will occur on 2369 Mar 24, lasting 105 minutes, 24 seconds. | 2441 May 06 | 2495 Jun 08 | 2603 Aug 13 | 2982 Mar 30 |
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 17–38 occur between 1801 and 2200: :
| 17 | 17 | 18 | 18 | 19 | 19 |
| 1810 Apr 19 | 1810 Apr 19 | 1828 Apr 29 | 1828 Apr 29 | 1846 May 11 | 1846 May 11 |
| 20 | 20 | 21 | 21 | 22 | 22 |
| 1864 May 21 | 1864 May 21 | 1882 Jun 01 | 1882 Jun 01 | 1900 Jun 13 | 1900 Jun 13 |
| 23 | 23 | 24 | 24 | 25 | 25 |
| 1918 Jun 24 | 1918 Jun 24 | 1936 Jul 04 | 1936 Jul 04 | 1954 Jul 16 | 1954 Jul 16 |
| 26 | 26 | 27 | 27 | 28 | 28 |
| 1972 Jul 26 | 1972 Jul 26 | 1990 Aug 06 | 1990 Aug 06 | 2008 Aug 16 | 2008 Aug 16 |
| 29 | 29 | 30 | 30 | 31 | 31 |
| 2026 Aug 28 | 2026 Aug 28 | 2044 Sep 07 | 2044 Sep 07 | 2062 Sep 18 | 2062 Sep 18 |
| 32 | 32 | 33 | 33 | 34 | 34 |
| 2080 Sep 29 | 2080 Sep 29 | 2098 Oct 10 | 2098 Oct 10 | 2116 Oct 21 | 2116 Oct 21 |
| 35 | 35 | 36 | 36 | 37 | 37 |
| 2134 Nov 02 | 2134 Nov 02 | 2152 Nov 12 | 2152 Nov 12 | 2170 Nov 23 | 2170 Nov 23 |
| 38 ||
| 2188 Dec 04 ||

### 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 2187 :
| 1805 Jan 15 (Saros 121) | 1805 Jan 15 (Saros 121) | 1815 Dec 16 (Saros 122) | 1815 Dec 16 (Saros 122) | 1826 Nov 14 (Saros 123) | 1826 Nov 14 (Saros 123) | 1837 Oct 13 (Saros 124) | 1837 Oct 13 (Saros 124) | 1848 Sep 13 (Saros 125) | 1848 Sep 13 (Saros 125) |
| 1859 Aug 13 (Saros 126) | 1859 Aug 13 (Saros 126) | 1870 Jul 12 (Saros 127) | 1870 Jul 12 (Saros 127) | 1881 Jun 12 (Saros 128) | 1881 Jun 12 (Saros 128) | 1892 May 11 (Saros 129) | 1892 May 11 (Saros 129) | 1903 Apr 12 (Saros 130) | 1903 Apr 12 (Saros 130) |
| 1914 Mar 12 (Saros 131) | 1914 Mar 12 (Saros 131) | 1925 Feb 08 (Saros 132) | 1925 Feb 08 (Saros 132) | 1936 Jan 08 (Saros 133) | 1936 Jan 08 (Saros 133) | 1946 Dec 08 (Saros 134) | 1946 Dec 08 (Saros 134) | 1957 Nov 07 (Saros 135) | 1957 Nov 07 (Saros 135) |
| 1968 Oct 06 (Saros 136) | 1968 Oct 06 (Saros 136) | 1979 Sep 06 (Saros 137) | 1979 Sep 06 (Saros 137) | 1990 Aug 06 (Saros 138) | 1990 Aug 06 (Saros 138) | 2001 Jul 05 (Saros 139) | 2001 Jul 05 (Saros 139) | 2012 Jun 04 (Saros 140) | 2012 Jun 04 (Saros 140) |
| 2023 May 05 (Saros 141) | 2023 May 05 (Saros 141) | 2034 Apr 03 (Saros 142) | 2034 Apr 03 (Saros 142) | 2045 Mar 03 (Saros 143) | 2045 Mar 03 (Saros 143) | 2056 Feb 01 (Saros 144) | 2056 Feb 01 (Saros 144) | 2066 Dec 31 (Saros 145) | 2066 Dec 31 (Saros 145) |
| 2077 Nov 29 (Saros 146) | 2077 Nov 29 (Saros 146) | 2088 Oct 30 (Saros 147) | 2088 Oct 30 (Saros 147) | 2099 Sep 29 (Saros 148) | 2099 Sep 29 (Saros 148) | 2110 Aug 29 (Saros 149) | 2110 Aug 29 (Saros 149) | 2121 Jul 30 (Saros 150) | 2121 Jul 30 (Saros 150) |
| 2132 Jun 28 (Saros 151) | 2132 Jun 28 (Saros 151) | 2143 May 28 (Saros 152) | 2143 May 28 (Saros 152) | 2154 Apr 28 (Saros 153) | 2154 Apr 28 (Saros 153) | | | | |
| 2187 Jan 24 (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 :
| 1816 Dec 04 (Saros 132) | 1816 Dec 04 (Saros 132) | 1845 Nov 14 (Saros 133) | 1845 Nov 14 (Saros 133) | 1874 Oct 25 (Saros 134) | 1874 Oct 25 (Saros 134) |
| 1903 Oct 06 (Saros 135) | 1903 Oct 06 (Saros 135) | 1932 Sep 14 (Saros 136) | 1932 Sep 14 (Saros 136) | 1961 Aug 26 (Saros 137) | 1961 Aug 26 (Saros 137) |
| 1990 Aug 06 (Saros 138) | 1990 Aug 06 (Saros 138) | 2019 Jul 16 (Saros 139) | 2019 Jul 16 (Saros 139) | 2048 Jun 26 (Saros 140) | 2048 Jun 26 (Saros 140) |
| 2077 Jun 06 (Saros 141) | 2077 Jun 06 (Saros 141) | 2106 May 17 (Saros 142) | 2106 May 17 (Saros 142) | 2135 Apr 28 (Saros 143) | 2135 Apr 28 (Saros 143) |
| 2164 Apr 07 (Saros 144) | 2164 Apr 07 (Saros 144) | 2193 Mar 17 (Saros 145) | 2193 Mar 17 (Saros 145) |

### 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 total solar eclipses of Solar Saros 145.
| July 31, 1981 | August 11, 1999 |