May 1985 lunar eclipse
A total lunar eclipse occurred at the Moon’s descending node of orbit on Saturday, May 4, 1985, with an umbral magnitude of 1.2369. A lunar eclipse occurs when the Moon moves into the Earth's shadow, causing the Moon to be darkened. A total lunar eclipse occurs when the Moon's near side entirely passes into the Earth's umbral shadow. 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. A total lunar eclipse can last up to nearly two hours, while a total solar eclipse lasts only a few minutes at any given place, because the Moon's shadow is smaller. Occurring only about 13.5 hours after perigee, the Moon's apparent diameter was larger.
This lunar eclipse was the first of a tetrad, with four total lunar eclipses in series, the others being on October 28, 1985; April 24, 1986; and October 17, 1986.
Visibility
The eclipse was completely visible over central and east Africa, eastern Europe, the western half of Asia, western Australia, and Antarctica, seen rising over much of South America, west Africa, and western Europe and setting over east and northeast Asia and much of Australia.Eclipse details
Shown below is a table displaying details about this particular solar eclipse. It describes various parameters pertaining to this eclipse.| Parameter | Value |
| Penumbral Magnitude | 2.18702 |
| Umbral Magnitude | 1.23687 |
| Gamma | 0.35197 |
| Sun Right Ascension | 02h47m17.2s |
| Sun Declination | +16°07'37.7" |
| Sun Semi-Diameter | 15'51.5" |
| Sun Equatorial Horizontal Parallax | 08.7" |
| Moon Right Ascension | 14h47m52.0s |
| Moon Declination | -15°47'45.9" |
| Moon Semi-Diameter | 16'41.4" |
| Moon Equatorial Horizontal Parallax | 1°01'15.3" |
| ΔT | 54.5 s |
Eclipse season
This eclipse is part of an eclipse season, a period, roughly every six months, when eclipses occur. Only two eclipse seasons occur each year, and each season lasts about 35 days and repeats just short of six months 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.| May 4 Descending node | May 19 Ascending node |
| Total lunar eclipse Lunar Saros 121 | Partial solar eclipse Solar Saros 147 |
Related eclipses
Eclipses in 1985
A total lunar eclipse on May 4.- A partial solar eclipse on May 19.
- A total lunar eclipse on October 28.
- A total solar eclipse on November 12.
Metonic
- Preceded by: Lunar eclipse of July 17, 1981
- Followed by: Lunar eclipse of February 20, 1989
Tzolkinex
- Preceded by: Lunar eclipse of March 24, 1978
- Followed by: Lunar eclipse of June 15, 1992
Half-Saros
- Preceded by: Solar eclipse of April 29, 1976
- Followed by: Solar eclipse of May 10, 1994
Tritos
- Preceded by: Lunar eclipse of June 4, 1974
- Followed by: Lunar eclipse of April 4, 1996
Lunar Saros 121
- Preceded by: Lunar eclipse of April 24, 1967
- Followed by: Lunar eclipse of May 16, 2003
Inex
- Preceded by: Lunar eclipse of May 24, 1956
- Followed by: Lunar eclipse of April 15, 2014
Triad
- Preceded by: Lunar eclipse of July 3, 1898
- Followed by: Lunar eclipse of March 4, 2072
Half-Saros cycle
A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days. This lunar eclipse is related to two annular solar eclipses of Solar Saros 128.| April 29, 1976 | May 10, 1994 |