January 1991 lunar eclipse

{{Infobox lunar eclipse

| type = penumbral

| image = Lunar eclipse chart close-1991Jan30.png

| caption = The Moon's hourly motion shown right to left

| date = January 30, 1991

| gamma = −1.0752

| magnitude = −0.1106

| saros_ser = 143

| saros_no = 17 of 73

| penumbral = 237 minutes, 28 seconds

| p1 = 3:59:55

| greatest = 5:58:40

| p4 = 7:57:23

| previous = August 1990

| next = June 1991

}}

A penumbral lunar eclipse occurred at the Moon’s descending node of orbit on Wednesday, January 30, 1991,{{cite web|title=January 29–30, 1991 Penumbral Lunar Eclipse|url=https://www.timeanddate.com/eclipse/lunar/1991-january-30|publisher=timeanddate|access-date=7 January 2025}} with an umbral magnitude of −0.1106. 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 1.9 days after perigee (on January 28, 1991, at 8:35 UTC), the Moon's apparent diameter was larger.{{cite web|title=Moon Distances for London, United Kingdom, England|url=https://www.timeanddate.com/astronomy/moon/distance.html?year=1991&n=136|publisher=timeanddate|access-date=7 January 2025}}

This eclipse was the first of four lunar eclipses in 1991, with the others occurring on June 27 (penumbral), July 26 (penumbral), and December 21 (partial).

Visibility

The eclipse was completely visible over North and South America, seen rising over northeast Asia and the central Pacific Ocean and setting over much of Africa and Europe.{{cite web|title=Penumbral Lunar Eclipse of 1991 Jan 30|url=https://eclipse.gsfc.nasa.gov/LEplot/LEplot1951/LE1991Jan30N.pdf|publisher=NASA|access-date=7 January 2025}}

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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.{{cite web|title=Penumbral Lunar Eclipse of 1991 Jan 30|url=https://eclipsewise.com/lunar/LEprime/1901-2000/LE1991Jan30Nprime.html|publisher=EclipseWise.com|access-date=7 January 2025}}

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|+January 30, 1991 Lunar Eclipse Parameters

! Parameter

! Value

Penumbral Magnitude

| 0.88079

Umbral Magnitude

| −0.11060

Gamma

| −1.07522

Sun Right Ascension

| 20h49m07.1s

Sun Declination

| -17°47'12.6"

Sun Semi-Diameter

| 16'14.2"

Sun Equatorial Horizontal Parallax

| 08.9"

Moon Right Ascension

| 08h47m30.0s

Moon Declination

| +16°46'53.1"

Moon Semi-Diameter

| 16'22.7"

Moon Equatorial Horizontal Parallax

| 1°00'06.5"

ΔT

| 57.6 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.

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|+ Eclipse season of January 1991

! January 15
Ascending node (new moon)
!! January 30
Descending node (full moon)

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| Annular solar eclipse
Solar Saros 131

Penumbral lunar eclipse
Lunar Saros 143

Related eclipses

= Eclipses in 1991 =

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 =

Preceded by: Lunar eclipse of April 14, 1987
Followed by: Lunar eclipse of November 18, 1994

= Tzolkinex =

Preceded by: Lunar eclipse of December 20, 1983
Followed by: Lunar eclipse of March 13, 1998

= Half-Saros =

Preceded by: Solar eclipse of January 25, 1982
Followed by: Solar eclipse of February 5, 2000

= Tritos =

Preceded by: Lunar eclipse of March 1, 1980
Followed by: Lunar eclipse of December 30, 2001

= Lunar Saros 143 =

Preceded by: Lunar eclipse of January 18, 1973
Followed by: Lunar eclipse of February 9, 2009

= Inex =

Preceded by: Lunar eclipse of February 19, 1962
Followed by: Lunar eclipse of January 10, 2020

= Triad =

Preceded by: Lunar eclipse of March 31, 1904
Followed by: Lunar eclipse of November 29, 2077

= Lunar eclipses of 1988–1991 =

= Saros 143 =

= Tritos series =

= Inex series =

= Half-Saros cycle =

A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days (a half saros).Mathematical Astronomy Morsels, Jean Meeus, p.110, Chapter 18, The half-saros This lunar eclipse is related to two partial solar eclipses of Solar Saros 150.

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