| Penumbral eclipse | |||||||||
 The Moon's hourly motion shown right to left | |||||||||
| Date | August 17, 2027 | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Gamma | 1.2797 | ||||||||
| Magnitude | −0.5234 | ||||||||
| Saros cycle | 148 (4 of 71) | ||||||||
| Penumbral | 218 minutes, 35 seconds | ||||||||
| |||||||||
A penumbrallunar eclipse will occur at the Moon’sascending node of orbit on Tuesday, August 17, 2027,[1] with an umbralmagnitude of −0.5234. A lunar eclipse occurs when theMoon moves into theEarth'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 asolar eclipse, which can only be viewed from a relatively small area of the world, a lunar eclipse may be viewed from anywhere on thenight side of Earth. Occurring about 1.9 days afterapogee (on August 15, 2027, at 10:20 UTC), the Moon's apparent diameter will be smaller.[2]
The eclipse will be completely visible overNorth andSouth America, seen rising overAustralia and the centralPacific Ocean and setting overwest Africa.[3]
 |
Shown below is a table displaying details about this particular eclipse. It describes various parameters pertaining to this eclipse.[4]
| Parameter | Value |
|---|---|
| Penumbral Magnitude | 0.54758 |
| Umbral Magnitude | −0.52344 |
| Gamma | 1.27974 |
| Sun Right Ascension | 09h45m58.6s |
| Sun Declination | +13°27'30.2" |
| Sun Semi-Diameter | 15'47.8" |
| Sun Equatorial Horizontal Parallax | 08.7" |
| Moon Right Ascension | 21h43m58.8s |
| Moon Declination | -12°24'40.9" |
| Moon Semi-Diameter | 14'44.9" |
| Moon Equatorial Horizontal Parallax | 0°54'07.8" |
| ΔT | 72.8 s |
This eclipse is part of aneclipse 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 afortnight. The first and last eclipse in this sequence is separated by onesynodic month.
| July 18 Ascending node (full moon) | August 2 Descending node (new moon) | August 17 Ascending node (full moon) |
|---|---|---|
 |  | |
| Penumbral lunar eclipse Lunar Saros 110 | Total solar eclipse Solar Saros 136 | Penumbral lunar eclipse Lunar Saros 148 |
This eclipse is a member of asemester series. An eclipse in a semester series of lunar eclipses repeats approximately every 177 days and 4 hours (a semester) at alternatingnodes of the Moon's orbit.[5]
The penumbral lunar eclipse onJuly 18, 2027 occurs in the next lunar year eclipse set.
| Lunar eclipse series sets from 2024 to 2027 | ||||||||
|---|---|---|---|---|---|---|---|---|
| Descending node | Ascending node | |||||||
| Saros | Date Viewing | Type Chart | Gamma | Saros | Date Viewing | Type Chart | Gamma | |
113 | 2024 Mar 25 | Penumbral | 1.0610 | 118 | 2024 Sep 18 | Partial | −0.9792 | |
123 | 2025 Mar 14 | Total | 0.3485 | 128 | 2025 Sep 07 | Total | −0.2752 | |
| 133 | 2026 Mar 03 | Total | −0.3765 | 138 | 2026 Aug 28 | Partial | 0.4964 | |
| 143 | 2027 Feb 20 | Penumbral | −1.0480 | 148 | 2027 Aug 17 | Penumbral | 1.2797 | |
TheMetonic cycle repeats nearly exactly every 19 years and represents aSaros cycle plus one lunar year. Because it occurs on the same calendar date, the Earth's shadow will in nearly the same location relative to the background stars.
| Descending node | Ascending node | |||||
|---|---|---|---|---|---|---|
| Saros | Date | Type | Saros | Date | Type | |
| 103 | 1951 Feb 21.88 | Penumbral | 108 | 1951 Aug 17.13 | Penumbral | |
 |  | |||||
| 113 | 1970 Feb 21.35 | Partial | 118 | 1970 Aug 17.14 | Partial | |
 |  | |||||
| 123 | 1989 Feb 20.64 | Total | 128 | 1989 Aug 17.13 | Total | |
 |  | |||||
| 133 | 2008 Feb 21.14 | Total | 138 | 2008 Aug 16.88 | Partial | |
 |  | |||||
| 143 | 2027 Feb 20.96 | Penumbral | 148 | 2027 Aug 17.30 | Penumbral | |
 |  | |||||
This eclipse is a part ofSaros series 148, repeating every 18 years, 11 days, and containing 70 events. The series started with a penumbral lunar eclipse onJuly 15, 1973. It contains partial eclipses from October 10, 2117 through May 5, 2460; total eclipses from May 17, 2478 through September 14, 2676; and a second set of partial eclipses from September 25, 2694 through May 25, 3091. The series ends at member 70 as a penumbral eclipse on August 9, 3217.
The longest duration of totality will be produced by member 37 at 104 minutes, 29 seconds on July 10, 2568. All eclipses in this series occur at the Moon’sascending node of orbit.[6]
| Greatest | First | |||
|---|---|---|---|---|
| The greatest eclipse of the series will occur on2568 Jul 10, lasting 104 minutes, 29 seconds.[7] | Penumbral | Partial | Total | Central |
1973 Jul 15 | 2117 Oct 10 | 2478 May 25 | 2514 Jun 08 | |
| Last | ||||
| Central | Total | Partial | Penumbral | |
| 2622 Aug 13 | 2676 Sep 14 | 3091 May 25 | 3217 Aug 09 | |
Eclipses are tabulated in three columns; every third eclipse in the same column is oneexeligmos apart, so they all cast shadows over approximately the same parts of the Earth.
| Series members 1–13 occur between 1973 and 2200: | |||||
|---|---|---|---|---|---|
| 1 | 2 | 3 | |||
| 1973 Jul 15 | 1991 Jul 26 | 2009 Aug 06 | |||
|  |  |  |  |  |
| 4 | 5 | 6 | |||
| 2027 Aug 17 | 2045 Aug 27 | 2063 Sep 07 | |||
| |  |  | ||
| 7 | 8 | 9 | |||
| 2081 Sep 18 | 2099 Sep 29 | 2117 Oct 10 | |||
 |  | ||||
| 10 | 11 | 12 | |||
| 2135 Oct 22 | 2153 Nov 01 | 2171 Nov 12 | |||
| 13 | |||||
| 2189 Nov 22 | |||||
This eclipse is a part of atritos cycle, repeating at alternating nodes every 135synodic months (≈ 3986.63 days, or 11 years minus 1 month). Their appearance and longitude are irregular due to a lack of synchronization with theanomalistic 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 2147 | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| 1809 Apr 30 (Saros 128) | 1820 Mar 29 (Saros 129) | 1831 Feb 26 (Saros 130) | 1842 Jan 26 (Saros 131) | 1852 Dec 26 (Saros 132) | |||||
| 1863 Nov 25 (Saros 133) | 1874 Oct 25 (Saros 134) | 1885 Sep 24 (Saros 135) | 1896 Aug 23 (Saros 136) | 1907 Jul 25 (Saros 137) | |||||
 |  | ||||||||
| 1918 Jun 24 (Saros 138) | 1929 May 23 (Saros 139) | 1940 Apr 22 (Saros 140) | 1951 Mar 23 (Saros 141) | 1962 Feb 19 (Saros 142) | |||||
 |  |  |  |  |  |  |  |  |  |
| 1973 Jan 18 (Saros 143) | 1983 Dec 20 (Saros 144) | 1994 Nov 18 (Saros 145) | 2005 Oct 17 (Saros 146) | 2016 Sep 16 (Saros 147) | |||||
 |  |  |  |  |  |  |  |  |  |
| 2027 Aug 17 (Saros 148) | 2038 Jul 16 (Saros 149) | 2049 Jun 15 (Saros 150) | |||||||
| |  |  |  |  | ||||
| 2114 Dec 12 (Saros 156) | |||||||||
| 2147 Sep 09 (Saros 159) | |||||||||
This eclipse is a part of the long periodinex cycle, repeating at alternating nodes, every 358synodic months (≈ 10,571.95 days, or 29 years minus 20 days). Their appearance and longitude are irregular due to a lack of synchronization with theanomalistic 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 | |||||
|---|---|---|---|---|---|
| 1825 Jan 04 (Saros 141) | 1853 Dec 15 (Saros 142) | 1882 Nov 25 (Saros 143) | |||
| 1911 Nov 06 (Saros 144) | 1940 Oct 16 (Saros 145) | 1969 Sep 25 (Saros 146) | |||
 |  |  |  |  |  |
| 1998 Sep 06 (Saros 147) | 2027 Aug 17 (Saros 148) | 2056 Jul 26 (Saros 149) | |||
 |  | | |  |  |
| 2085 Jul 07 (Saros 150) | 2114 Jun 18 (Saros 151) | 2143 May 28 (Saros 152) | |||
| 2172 May 08 (Saros 153) | |||||
A lunar eclipse will be preceded and followed by solar eclipses by 9 years and 5.5 days (ahalf saros).[8] This lunar eclipse is related to two partial solar eclipses ofSolar Saros 155.
| August 11, 2018 | August 21, 2036 |
|---|---|
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