April 1977 lunar eclipse
| Partial eclipse | |||||||||||||
 The Moon's hourly motion shown right to left | |||||||||||||
| Date | April 4, 1977 | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Gamma | −0.9148 | ||||||||||||
| Magnitude | 0.1929 | ||||||||||||
| Saros cycle | 112 (63 of 72) | ||||||||||||
| Partiality | 94 minutes, 44 seconds | ||||||||||||
| Penumbral | 262 minutes, 52 seconds | ||||||||||||
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A partial lunar eclipse occurred at the Moon’s ascending node of orbit on Monday, April 4, 1977,[1] with an umbral magnitude of 0.1929. 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 1.7 days before perigee (on April 5, 1977, at 21:50 UTC), the Moon's apparent diameter was larger.[2]
Visibility
The eclipse was completely visible over much of North America, South America, and west Africa, seen rising over western North America and the central Pacific Ocean and setting over Africa, Europe and the Middle East.[3]
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Eclipse details
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 | 1.16570 |
| Umbral Magnitude | 0.19289 |
| Gamma | −0.91483 |
| Sun Right Ascension | 00h52m35.5s |
| Sun Declination | +05°37'56.4" |
| Sun Semi-Diameter | 15'59.4" |
| Sun Equatorial Horizontal Parallax | 08.8" |
| Moon Right Ascension | 12h51m29.8s |
| Moon Declination | -06°30'38.9" |
| Moon Semi-Diameter | 16'26.2" |
| Moon Equatorial Horizontal Parallax | 1°00'19.6" |
| ΔT | 47.8 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.
| April 4 Ascending node (full moon) |
April 18 Descending node (new moon) |
|---|---|
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| Partial lunar eclipse Lunar Saros 112 |
Annular solar eclipse Solar Saros 138 |
Related eclipses
Eclipses in 1977
- A partial lunar eclipse on April 4.
- An annular solar eclipse on April 18.
- A penumbral lunar eclipse on September 27.
- A total solar eclipse on October 12.
Metonic
- Preceded by: Lunar eclipse of June 15, 1973
- Followed by: Lunar eclipse of January 20, 1981
Tzolkinex
- Preceded by: Lunar eclipse of February 21, 1970
- Followed by: Lunar eclipse of May 15, 1984
Half-Saros
- Preceded by: Solar eclipse of March 28, 1968
- Followed by: Solar eclipse of April 9, 1986
Tritos
- Preceded by: Lunar eclipse of May 4, 1966
- Followed by: Lunar eclipse of March 3, 1988
Lunar Saros 112
- Preceded by: Lunar eclipse of March 24, 1959
- Followed by: Lunar eclipse of April 15, 1995
Inex
- Preceded by: Lunar eclipse of April 23, 1948
- Followed by: Lunar eclipse of March 14, 2006
Triad
- Preceded by: Lunar eclipse of June 3, 1890
- Followed by: Lunar eclipse of February 2, 2064
Lunar eclipses of 1977–1980
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.[5]
The penumbral lunar eclipse on July 27, 1980 occurs in the next lunar year eclipse set.
| Lunar eclipse series sets from 1977 to 1980 | ||||||||
|---|---|---|---|---|---|---|---|---|
| Ascending node | Descending node | |||||||
| Saros | Date Viewing |
Type Chart |
Gamma | Saros | Date Viewing |
Type Chart |
Gamma | |
| 112 | 1977 Apr 04
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Partial
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−0.9148 | 117 | 1977 Sep 27
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Penumbral
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1.0768 | |
| 122 | 1978 Mar 24
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Total
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−0.2140 | 127 | 1978 Sep 16
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Total
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0.2951 | |
| 132 | 1979 Mar 13
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Partial
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0.5254 | 137 | 1979 Sep 06
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Total
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−0.4305 | |
| 142 | 1980 Mar 01
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Penumbral
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1.2270 | 147 | 1980 Aug 26
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Penumbral
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−1.1608 | |
Saros 112
This eclipse is a part of Saros series 112, repeating every 18 years, 11 days, and containing 72 events. The series started with a penumbral lunar eclipse on May 20, 859 AD. It contains partial eclipses from August 3, 985 AD through March 8, 1346; total eclipses from March 18, 1364 through August 27, 1616; and a second set of partial eclipses from September 7, 1634 through April 25, 2013. The series ends at member 72 as a penumbral eclipse on July 12, 2139.
The longest duration of totality was produced by member 36 at 99 minutes, 51 seconds on June 2, 1490. All eclipses in this series occur at the Moon’s ascending node of orbit.[6]
| Greatest | First | |||
|---|---|---|---|---|
| The greatest eclipse of the series occurred on 1490 Jun 02, lasting 99 minutes, 51 seconds.[7] | Penumbral | Partial | Total | Central |
| 859 May 20 |
985 Aug 03 |
1364 Mar 18 |
1436 Apr 30 | |
| Last | ||||
| Central | Total | Partial | Penumbral | |
| 1562 Jul 16 |
1616 Aug 27 |
2013 Apr 25
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2139 Jul 12 | |
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 54–72 occur between 1801 and 2139: | |||||
|---|---|---|---|---|---|
| 54 | 55 | 56 | |||
| 1814 Dec 26 | 1833 Jan 06 | 1851 Jan 17 | |||
| 57 | 58 | 59 | |||
| 1869 Jan 28 | 1887 Feb 08 | 1905 Feb 19 | |||
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| 60 | 61 | 62 | |||
| 1923 Mar 03 | 1941 Mar 13 | 1959 Mar 24 | |||
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| 63 | 64 | 65 | |||
| 1977 Apr 04 | 1995 Apr 15 | 2013 Apr 25 | |||
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| 66 | 67 | 68 | |||
| 2031 May 07 | 2049 May 17 | 2067 May 28 | |||
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| 69 | 70 | 71 | |||
| 2085 Jun 08 | 2103 Jun 20 | 2121 Jun 30 | |||
| 72 | |||||
| 2139 Jul 12 | |||||
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 1835 and 2200 | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| 1835 May 12 (Saros 99) |
1846 Apr 11 (Saros 100) |
1868 Feb 08 (Saros 102) |
1879 Jan 08 (Saros 103) | ||||||
| 1933 Aug 05 (Saros 108) | |||||||||
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| 1944 Jul 06 (Saros 109) |
1955 Jun 05 (Saros 110) |
1966 May 04 (Saros 111) |
1977 Apr 04 (Saros 112) |
1988 Mar 03 (Saros 113) | |||||
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| 1999 Jan 31 (Saros 114) |
2009 Dec 31 (Saros 115) |
2020 Nov 30 (Saros 116) |
2031 Oct 30 (Saros 117) |
2042 Sep 29 (Saros 118) | |||||
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| 2053 Aug 29 (Saros 119) |
2064 Jul 28 (Saros 120) |
2075 Jun 28 (Saros 121) |
2086 May 28 (Saros 122) |
2097 Apr 26 (Saros 123) | |||||
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| 2108 Mar 27 (Saros 124) |
2119 Feb 25 (Saros 125) |
2130 Jan 24 (Saros 126) |
2140 Dec 23 (Saros 127) |
2151 Nov 24 (Saros 128) | |||||
| 2162 Oct 23 (Saros 129) |
2173 Sep 21 (Saros 130) |
2184 Aug 21 (Saros 131) |
2195 Jul 22 (Saros 132) | ||||||
Half-Saros cycle
A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days (a half saros).[8] This lunar eclipse is related to two partial solar eclipses of Solar Saros 119.
| March 28, 1968 | April 9, 1986 |
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See also
Notes
- ^ "April 3–4, 1977 Partial Lunar Eclipse". timeanddate. Retrieved 4 January 2025.
- ^ "Moon Distances for London, United Kingdom, England". timeanddate. Retrieved 4 January 2025.
- ^ "Partial Lunar Eclipse of 1977 Apr 04" (PDF). NASA. Retrieved 4 January 2025.
- ^ "Partial Lunar Eclipse of 1977 Apr 04". EclipseWise.com. Retrieved 4 January 2025.
- ^ van Gent, R.H. "Solar- and Lunar-Eclipse Predictions from Antiquity to the Present". A Catalogue of Eclipse Cycles. Utrecht University. Retrieved 6 October 2018.
- ^ "NASA - Catalog of Lunar Eclipses of Saros 112". eclipse.gsfc.nasa.gov.
- ^ Listing of Eclipses of series 112
- ^ Mathematical Astronomy Morsels, Jean Meeus, p.110, Chapter 18, The half-saros
External links
- 1977 Apr 04 chart Eclipse Predictions by Fred Espenak, NASA/GSFC
