July 1991 lunar eclipse
| Penumbral eclipse | |||||||||
 The Moon's hourly motion shown right to left | |||||||||
| Date | July 26, 1991 | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Gamma | 1.4370 | ||||||||
| Magnitude | −0.8109 | ||||||||
| Saros cycle | 148 (2 of 71) | ||||||||
| Penumbral | 152 minutes, 42 seconds | ||||||||
| |||||||||
A penumbral lunar eclipse occurred at the Moon’s ascending node of orbit on Friday, July 26, 1991,[1] with an umbral magnitude of −0.8109. 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 2.25 days after apogee (on July 24, 1991, at 12:10 UTC), the Moon's apparent diameter was smaller.[2]
This eclipse was the third of four lunar eclipses in 1991, with the others occurring on January 30 (penumbral), June 27 (penumbral), and December 21 (partial).
Visibility
[edit]The eclipse was completely visible over east Africa, much of Asia, Australia, and Antarctica, seen rising over much of Europe and west and central Africa and setting over northeast Asia and the central Pacific Ocean.[3]
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Eclipse details
[edit]Shown below is a table displaying details about this particular solar eclipse. It describes various parameters pertaining to this eclipse.[4]
| Parameter | Value |
|---|---|
| Penumbral Magnitude | 0.25425 |
| Umbral Magnitude | −0.81093 |
| Gamma | 1.43698 |
| Sun Right Ascension | 08h22m14.5s |
| Sun Declination | +19°25'45.6" |
| Sun Semi-Diameter | 15'44.9" |
| Sun Equatorial Horizontal Parallax | 08.7" |
| Moon Right Ascension | 20h20m28.0s |
| Moon Declination | -18°11'58.5" |
| Moon Semi-Diameter | 14'47.1" |
| Moon Equatorial Horizontal Parallax | 0°54'15.7" |
| ΔT | 58.0 s |
Eclipse season
[edit]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. The first and last eclipse in this sequence is separated by one synodic month.
| June 27 Ascending node (full moon) |
July 11 Descending node (new moon) |
July 26 Ascending node (full moon) |
|---|---|---|
 |
 |
|
| Penumbral lunar eclipse Lunar Saros 110 |
Total solar eclipse Solar Saros 136 |
Penumbral lunar eclipse Lunar Saros 148 |
Related eclipses
[edit]Eclipses in 1991
[edit]- 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
[edit]- Preceded by: Lunar eclipse of October 7, 1987
Tzolkinex
[edit]- Preceded by: Lunar eclipse of June 13, 1984
- Followed by: Lunar eclipse of September 6, 1998
Half-Saros
[edit]- Preceded by: Solar eclipse of July 20, 1982
- Followed by: Solar eclipse of July 31, 2000
Tritos
[edit]- Preceded by: Lunar eclipse of August 26, 1980
- Followed by: Lunar eclipse of June 24, 2002
Lunar Saros 148
[edit]- Preceded by: Lunar eclipse of July 15, 1973
- Followed by: Lunar eclipse of August 6, 2009
Inex
[edit]- Preceded by: Lunar eclipse of August 15, 1962
- Followed by: Lunar eclipse of July 5, 2020
Triad
[edit]- Preceded by: Lunar eclipse of September 24, 1904
Lunar eclipses of 1988–1991
[edit]| Lunar eclipse series sets from 1988–1991 | ||||||||
|---|---|---|---|---|---|---|---|---|
| Descending node | Ascending node | |||||||
| Saros | Date viewing |
Type chart |
Gamma | Saros | Date viewing |
Type chart |
Gamma | |
| 113 | 1988 Mar 03
|
Penumbral
|
0.98855 | 118 | 1988 Aug 27
|
Partial
|
−0.86816 | |
| 123 | 1989 Feb 20
|
Total 
|
0.29347 | 128 | 1989 Aug 17
|
Total
|
−0.14905 | |
| 133 | 1990 Feb 09
|
Total
|
−0.41481 | 138 | 1990 Aug 06
|
Partial
|
0.63741 | |
| 143 | 1991 Jan 30
|
Penumbral
|
−1.07522 | 148 | 1991 Jul 26
|
Penumbral
|
1.43698 | |
| Last set | 1987 Apr 14 | Last set | 1987 Oct 07 | |||||
| Next set | 1991 Dec 21 | Next set | 1991 Jun 27 | |||||
Saros 148
[edit]This eclipse is part of Saros cycle series 148.
Half-Saros cycle
[edit]A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days (a half saros).[5] This lunar eclipse is related to two partial solar eclipses of Solar Saros 155.
| July 20, 1982 | July 31, 2000 |
|---|---|
|
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See also
[edit]Notes
[edit]- ^ "July 26–27, 1991 Penumbral Lunar Eclipse". timeanddate. Retrieved 8 January 2025.
- ^ "Moon Distances for London, United Kingdom, England". timeanddate. Retrieved 8 January 2025.
- ^ "Penumbral Lunar Eclipse of 1991 Jul 26" (PDF). NASA. Retrieved 8 January 2025.
- ^ "Penumbral Lunar Eclipse of 1991 Jun 27". EclipseWise.com. Retrieved 8 January 2025.
- ^ Mathematical Astronomy Morsels, Jean Meeus, p.110, Chapter 18, The half-saros
External links
[edit]- 1991 Jul 26 chart Eclipse Predictions by Fred Espenak, NASA/GSFC
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