Solar eclipse of April 29, 1976

An annular solar eclipse occurred at the Moon's descending node of orbit on Thursday, April 29, 1976,^[1] with a magnitude of 0.9421. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide. Occurring about 1.9 days after apogee (on April 27, 1976, at 13:30 UTC), the Moon's apparent diameter was smaller.^[2]

Solar eclipse of April 29, 1976

Annular eclipse
Map
Gamma	0.3378
Magnitude	0.9421
Maximum eclipse
Duration	401 s (6 min 41 s)
Coordinates	34°N 18.3°E / 34; 18.3
Max. width of band	227 km (141 mi)
Times (UTC)
Greatest eclipse	10:24:18
References
Saros	128 (56 of 73)
Catalog # (SE5000)	9456
← November 3, 1975 October 23, 1976 →

Annularity was visible from North Africa, Greece, Turkey, Middle East, central Asia, India, China. 5 of the 14 eight-thousanders in Pakistan and China—Nanga Parbat, K2, Broad Peak, Gasherbrum II and Gasherbrum I, lie in the path of annularity. A partial eclipse was visible for parts of the Canadian Maritimes, North Africa, Central Africa, Europe, the Middle East, Central Asia, and South Asia.

Note that the central line of this annular solar eclipse followed a path extremely similar to that of the total eclipse that will occur 112 years later on April 21, 2088.

Observation

The Institute of Physics and Institute of Mathematics of the Chinese Academy of Sciences and the Xinjiang Earthquake Team conducted observations of gravitational effects using gravimeters, inclinometers, pendulum clocks and seismometers in southwestern Hotan County, Hotan Prefecture, Xinjiang near the Karakoram Pass at an altitude of 5,500 metres (18,000 ft). Results showed that the gravitational acceleration had no obvious effect within the accuracy of the instruments. No inclination was recorded on the photosensitive paper of the inclinometer due to the width of its lines. Three inclinations were pen-recorded, whose time and direction were clearly related to that of the eclipse. Due to the difficult conditions with the high altitude, the observation team was unable to obtain more comparative data.^[3]

Eclipse details

Shown below are two tables displaying details about this particular solar eclipse. The first table outlines times at which the moon's penumbra or umbra attains the specific parameter, and the second table describes various other parameters pertaining to this eclipse.^[4]

April 29, 1976 Solar Eclipse Times

Event	Time (UTC)
First Penumbral External Contact	1976 April 29 at 07:23:05.3 UTC
First Umbral External Contact	1976 April 29 at 08:30:13.1 UTC
First Central Line	1976 April 29 at 08:32:52.8 UTC
First Umbral Internal Contact	1976 April 29 at 08:35:32.9 UTC
First Penumbral Internal Contact	1976 April 29 at 09:52:32.8 UTC
Ecliptic Conjunction	1976 April 29 at 10:20:15.6 UTC
Greatest Eclipse	1976 April 29 at 10:24:17.7 UTC
Greatest Duration	1976 April 29 at 10:30:53.5 UTC
Equatorial Conjunction	1976 April 29 at 10:33:23.0 UTC
Last Penumbral Internal Contact	1976 April 29 at 10:55:47.8 UTC
Last Umbral Internal Contact	1976 April 29 at 12:12:56.6 UTC
Last Central Line	1976 April 29 at 12:15:35.7 UTC
Last Umbral External Contact	1976 April 29 at 12:18:14.3 UTC
Last Penumbral External Contact	1976 April 29 at 13:25:23.3 UTC

April 29, 1976 Solar Eclipse Parameters

Parameter	Value
Eclipse Magnitude	0.94208
Eclipse Obscuration	0.88752
Gamma	0.33783
Sun Right Ascension	02h27m19.6s
Sun Declination	+14°34'10.4"
Sun Semi-Diameter	15'52.7"
Sun Equatorial Horizontal Parallax	08.7"
Moon Right Ascension	02h27m02.8s
Moon Declination	+14°51'57.3"
Moon Semi-Diameter	14'44.9"
Moon Equatorial Horizontal Parallax	0°54'07.6"
ΔT	46.8 s

Eclipse season

See also: Eclipse cycle

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 April–May 1976

April 29 Descending node (new moon)	May 13 Ascending node (full moon)
Annular solar eclipse Solar Saros 128	Partial lunar eclipse Lunar Saros 140

Related eclipses

Eclipses in 1976

• An annular solar eclipse on April 29.
• A partial lunar eclipse on May 13.
• A total solar eclipse on October 23.
• A penumbral lunar eclipse on November 6.

Metonic

• Preceded by: Solar eclipse of July 10, 1972
• Followed by: Solar eclipse of February 16, 1980

Tzolkinex

• Preceded by: Solar eclipse of March 18, 1969
• Followed by: Solar eclipse of June 11, 1983

Half-Saros

• Preceded by: Lunar eclipse of April 24, 1967
• Followed by: Lunar eclipse of May 4, 1985

Tritos

• Preceded by: Solar eclipse of May 30, 1965
• Followed by: Solar eclipse of March 29, 1987

Solar Saros 128

• Preceded by: Solar eclipse of April 19, 1958
• Followed by: Solar eclipse of May 10, 1994

Inex

• Preceded by: Solar eclipse of May 20, 1947
• Followed by: Solar eclipse of April 8, 2005

Triad

• Preceded by: Solar eclipse of June 28, 1889
• Followed by: Solar eclipse of February 28, 2063

Solar eclipses of 1975–1978

This eclipse is a member of a semester series. An eclipse in a semester series of solar eclipses repeats approximately every 177 days and 4 hours (a semester) at alternating nodes of the Moon's orbit.^[5]

Solar eclipse series sets from 1975 to 1978
Descending node				Ascending node
Saros	Map	Gamma		Saros	Map	Gamma
118	May 11, 1975 Partial	1.0647		123	November 3, 1975 Partial	−1.0248
128	April 29, 1976 Annular	0.3378		133	October 23, 1976 Total	−0.327
138	April 18, 1977 Annular	−0.399		143	October 12, 1977 Total	0.3836
148	April 7, 1978 Partial	−1.1081		153	October 2, 1978 Partial	1.1616

Saros 128

This eclipse is a part of Saros series 128, repeating every 18 years, 11 days, and containing 73 events. The series started with a partial solar eclipse on August 29, 984 AD. It contains total eclipses from May 16, 1417 through June 18, 1471; hybrid eclipses from June 28, 1489 through July 31, 1543; and annular eclipses from August 11, 1561 through July 25, 2120. The series ends at member 73 as a partial eclipse on November 1, 2282. Its 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.

The longest duration of totality was produced by member 27 at 1 minutes, 45 seconds on June 7, 1453, and the longest duration of annularity was produced by member 48 at 8 minutes, 35 seconds on February 1, 1832. All eclipses in this series occur at the Moon’s descending node of orbit.^[6]

Series members 47–68 occur between 1801 and 2200:
47	48	49
January 21, 1814	February 1, 1832	February 12, 1850
50	51	52
February 23, 1868	March 5, 1886	March 17, 1904
53	54	55
March 28, 1922	April 7, 1940	April 19, 1958
56	57	58
April 29, 1976	May 10, 1994	May 20, 2012
59	60	61
June 1, 2030	June 11, 2048	June 22, 2066
62	63	64
July 3, 2084	July 15, 2102	July 25, 2120
65	66	67
August 5, 2138	August 16, 2156	August 27, 2174
68
September 6, 2192

Metonic series

The metonic series repeats eclipses every 19 years (6939.69 days), lasting about 5 cycles. Eclipses occur in nearly the same calendar date. In addition, the octon subseries repeats 1/5 of that or every 3.8 years (1387.94 days). All eclipses in this table occur at the Moon's descending node.

21 eclipse events between July 11, 1953 and July 11, 2029
July 10–11	April 29–30	February 15–16	December 4	September 21–23
116	118	120	122	124
July 11, 1953	April 30, 1957	February 15, 1961	December 4, 1964	September 22, 1968
126	128	130	132	134
July 10, 1972	April 29, 1976	February 16, 1980	December 4, 1983	September 23, 1987
136	138	140	142	144
July 11, 1991	April 29, 1995	February 16, 1999	December 4, 2002	September 22, 2006
146	148	150	152	154
July 11, 2010	April 29, 2014	February 15, 2018	December 4, 2021	September 21, 2025
156
July 11, 2029

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
September 8, 1801 (Saros 112)	August 7, 1812 (Saros 113)	July 8, 1823 (Saros 114)	June 7, 1834 (Saros 115)	May 6, 1845 (Saros 116)
April 5, 1856 (Saros 117)	March 6, 1867 (Saros 118)	February 2, 1878 (Saros 119)	January 1, 1889 (Saros 120)	December 3, 1899 (Saros 121)
November 2, 1910 (Saros 122)	October 1, 1921 (Saros 123)	August 31, 1932 (Saros 124)	August 1, 1943 (Saros 125)	June 30, 1954 (Saros 126)
May 30, 1965 (Saros 127)	April 29, 1976 (Saros 128)	March 29, 1987 (Saros 129)	February 26, 1998 (Saros 130)	January 26, 2009 (Saros 131)
December 26, 2019 (Saros 132)	November 25, 2030 (Saros 133)	October 25, 2041 (Saros 134)	September 22, 2052 (Saros 135)	August 24, 2063 (Saros 136)
July 24, 2074 (Saros 137)	June 22, 2085 (Saros 138)	May 22, 2096 (Saros 139)	April 23, 2107 (Saros 140)	March 22, 2118 (Saros 141)
February 18, 2129 (Saros 142)	January 20, 2140 (Saros 143)	December 19, 2150 (Saros 144)	November 17, 2161 (Saros 145)	October 17, 2172 (Saros 146)
September 16, 2183 (Saros 147)	August 16, 2194 (Saros 148)

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
August 28, 1802 (Saros 122)	August 7, 1831 (Saros 123)	July 18, 1860 (Saros 124)
June 28, 1889 (Saros 125)	June 8, 1918 (Saros 126)	May 20, 1947 (Saros 127)
April 29, 1976 (Saros 128)	April 8, 2005 (Saros 129)	March 20, 2034 (Saros 130)
February 28, 2063 (Saros 131)	February 7, 2092 (Saros 132)	January 19, 2121 (Saros 133)
December 30, 2149 (Saros 134)	December 9, 2178 (Saros 135)