A penumbral lunar eclipse occurred at the Moon’s ascending node of orbit on Sunday, July 15, 1973,[1] with an umbral magnitude of −0.9581. 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 3 days after apogee (on July 12, 1973, at 22:45 UTC), the Moon's apparent diameter was smaller.[2]
| Penumbral eclipse | |||||||||
 The Moon's hourly motion shown right to left | |||||||||
| Date | July 15, 1973 | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Gamma | 1.5178 | ||||||||
| Magnitude | −0.9581 | ||||||||
| Saros cycle | 148 (1 of 71) | ||||||||
| Penumbral | 99 minutes, 5 seconds | ||||||||
| |||||||||
This eclipse was the third of four lunar eclipses in 1973, with the others occurring on January 18 (penumbral), June 15 (penumbral), and December 10 (partial).
This was the first lunar eclipse of Saros series 148.
Visibility
editThe eclipse was completely visible over Australia, western North America, and Antarctica, seen rising over east Asia and setting over central North America and western South America.[3]
|
Eclipse details
editShown below is a table displaying details about this particular solar eclipse. It describes various parameters pertaining to this eclipse.[4]
| Parameter | Value |
|---|---|
| Penumbral Magnitude | 0.10468 |
| Umbral Magnitude | −0.95805 |
| Gamma | 1.51782 |
| Sun Right Ascension | 07h38m36.3s |
| Sun Declination | +21°30'35.7" |
| Sun Semi-Diameter | 15'44.1" |
| Sun Equatorial Horizontal Parallax | 08.7" |
| Moon Right Ascension | 19h37m04.9s |
| Moon Declination | -20°10'55.9" |
| Moon Semi-Diameter | 14'48.4" |
| Moon Equatorial Horizontal Parallax | 0°54'20.5" |
| ΔT | 43.9 s |
Eclipse season
editThis 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 15 Ascending node (full moon) |
June 30 Descending node (new moon) |
July 15 Ascending node (full moon) |
|---|---|---|
 |
 |
|
| Penumbral lunar eclipse Lunar Saros 110 |
Total solar eclipse Solar Saros 136 |
Penumbral lunar eclipse Lunar Saros 148 |
Related eclipses
editEclipses in 1973
edit- An annular solar eclipse on January 4.
- A penumbral lunar eclipse on January 18.
- A penumbral lunar eclipse on June 15.
- A total solar eclipse on June 30.
- A penumbral lunar eclipse on July 15.
- A partial lunar eclipse on December 10.
- An annular solar eclipse on December 24.
Metonic
edit- Preceded by: Lunar eclipse of September 25, 1969
Tzolkinex
edit- Followed by: Lunar eclipse of August 26, 1980
Half-Saros
edit- Preceded by: Solar eclipse of July 9, 1964
- Followed by: Solar eclipse of July 20, 1982
Tritos
edit- Preceded by: Lunar eclipse of August 15, 1962
- Followed by: Lunar eclipse of June 13, 1984
Lunar Saros 148
edit- Followed by: Lunar eclipse of July 26, 1991
Inex
edit- Preceded by: Lunar eclipse of August 4, 1944
- Followed by: Lunar eclipse of June 24, 2002
Triad
edit- Preceded by: Lunar eclipse of September 13, 1886
Lunar eclipses of 1969–1973
editThis 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 eclipses on April 2, 1969 and September 25, 1969 occur in the previous lunar year eclipse set, and the lunar eclipses on June 15, 1973 (penumbral) and December 10, 1973 (partial) occur in the next lunar year eclipse set.
| Lunar eclipse series sets from 1969 to 1973 | ||||||||
|---|---|---|---|---|---|---|---|---|
| Ascending node | Descending node | |||||||
| Saros | Date Viewing |
Type Chart |
Gamma | Saros | Date Viewing |
Type Chart |
Gamma | |
| 108 | 1969 Aug 27
|
Penumbral
|
−1.5407 | 113 | 1970 Feb 21
|
Partial
|
0.9620 | |
| 118 | 1970 Aug 17
|
Partial
|
−0.8053 | 123 | 1971 Feb 10
|
Total
|
0.2741 | |
| 128 | 1971 Aug 06
|
Total
|
−0.0794 | 133 | 1972 Jan 30
|
Total
|
−0.4273 | |
| 138 | 1972 Jul 26
|
Partial
|
0.7117 | 143 | 1973 Jan 18
|
Penumbral
|
−1.0845 | |
| 148 | 1973 Jul 15
|
Penumbral
|
1.5178 | |||||
Half-Saros cycle
editA lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days (a half saros).[6] This lunar eclipse is related to two partial solar eclipses of Solar Saros 155.
| July 9, 1964 | July 20, 1982 |
|---|---|
|
|
See also
editNotes
edit- ^ "July 15, 1973 Penumbral Lunar Eclipse". timeanddate. Retrieved 3 January 2025.
- ^ "Moon Distances for London, United Kingdom, England". timeanddate. Retrieved 3 January 2025.
- ^ "Penumbral Lunar Eclipse of 1973 Jul 15" (PDF). NASA. Retrieved 3 January 2025.
- ^ "Penumbral Lunar Eclipse of 1973 Jul 15". EclipseWise.com. Retrieved 3 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.
- ^ Mathematical Astronomy Morsels, Jean Meeus, p.110, Chapter 18, The half-saros
External links
edit- 1973 Jul 15 chart Eclipse Predictions by Fred Espenak, NASA/GSFC
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